Eunmi Choi

Kookmin University, Sŏul, Seoul, South Korea

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Publications (71)12.89 Total impact

  • Mino Ku · Eunmi Choi · Dugki Min
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    ABSTRACT: SUMMARY To process big data in a cloud computing environment, a large scale of stream big data is one of the challenging issues. In particular, complex event processing is an emerging technology to handle massive events from multiple sources and process them in a near real time. In this paper, we analyze four performance-influencing factors on a virtualized event processing system: the number of query statements, garbage collection intervals, the quantity of virtual machine resources, and virtual CPU assignment types. In our experiments, we observe the performance effects of these performance parameters, by implementing and running an Esper-based event processing application on top of a Xen-based virtualized system. With experimental results, we analyze the memory consumption problem, and apply periodic garbage collection, to reduce unexpected memory consumption of JVM. Also, we analyze performance effects of the number of cores in a virtual machine (VM) and resource sharing among VMs. Under the virtualized environment in cloud computing infrastructure, one of the critical issues is the management of virtualized computing resources. Accordingly, we present the event processing performance on VMs as a function of virtual CPU assignment types and the number of VMs that share virtual CPUs. Copyright © 2014 John Wiley & Sons, Ltd.
    No preview · Article · Jun 2014 · International Journal of Communication Systems
  • Don S · Duckwon Chung · Eunmi Choi · Dugki Min
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    ABSTRACT: Real-time remote health monitoring systems are experiencing tremendous advancement resulting from improvements in low power, reliable sensors; yet they are still constrained to low-level interpretation. Automatic data analysis continues to be a tedious task due to a lack of efficient, reliable platforms for data analysis. In this paper, we present a system for monitoring patients remotely by emphasizing the strength of Complex Event Processing (CEP) and Situation Awareness. In this approach, the system makes decisions in a declarative way, which helps medical experts to understand the situation in a more realistic manner. The primary objective of this paper is to explicate the different components inside the system. To verify the technical feasibility of each component, the proposed system is implemented and tested using ECG data.
    No preview · Article · Apr 2013 · Journal of Medical Systems
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    S. Don · Duckwon Chung · Dugki Min · Eunmi Choi
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    ABSTRACT: In this study, we present a three-stage method for detecting abnormalities and classifying electrocardiogram (ECG) beats using a k-nearest neighbor (k-NN) classifier and Gaussian mixture model (GMM). In the first stage, a signal filtering method is used to remove the ECG beat baseline wander. In the second stage, features are extracted based on Higuchi's fractal dimension (HFD) and statistical features. In the third stage, k-NN and GMM are used as classifiers to classify arrhythmia and ischemia. A total of 30,000 ECG segments obtained from the MIT-BIH Arrhythmia and European ST-T Ischemia databases were used to quantify this approach. 60% of the beats were used for training the classifier and the remaining 40%, for validating it. An overall accuracy of 99% and 98.24% was obtained for k-NN and GMM, respectively. This result is significantly better than that of currently used state-of-the-art classification approaches for arrhythmia and ischemia.
    Full-text · Article · Jan 2013 · Journal of Mechanics in Medicine and Biology
  • N. Mohan Krishna Varma · Eunmi Choi
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    ABSTRACT: The computational domain is becoming huge and complex. Cloud computing has begun as a general computing model to support processing large volumetric data using clusters of commodity computers. In recent years, there is a need for extension of Grid Infrastructure to provide dedicated resources to the user. Cloud computing can fulfill resource requirements with the help of virtualization technology. By integrating the cloud computing with grid infrastructure, resource usage can be satisfied as per user demand. In this paper Globus toolkit is used as the grid middleware for the extension of the grid infrastructure using eucalyptus cloud environment. Virtual machines deployed at the Grid resource would satisfy the needs of the user application. Virtualization in the context of Grid can be implemented by combining the GT4 and Eucalyptus features. Globus tool kit, the middleware for Grid computing added the virtual machines via the Eucalyptus to extend the Grid computing environment to access the external Cloud environment. Grid computing community shows research interests in deploying computing systems or test beds with virtual machines. The extension of the GT4 grid middleware using Eucalyptus cloud environment will help the user to execute the jobs remotely with maximum utilization of the resources.
    No preview · Chapter · Jan 2013
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    ABSTRACT: In the past decades there has been substantial research undergone in design of intelligent architecture for Rotorcraft based Unmanned Aerial Vehicle (RUAV). Designing intelligent architecture is a challenging problem since future RUAV’s are utterly autonomous and their performance is comparable to that of manned vehicles. This paper deals with design and development of a layered architectural framework which addresses the issue arising in autonomous intelligent control system. The architecture consists of two layers: the high-level layer occupied by planning routines. In this level the way-points, mission tasks from command center is executed. The low-level layer function is to stabilize the flight and follow the commanded trajectory from upper layer. These layers integrate the following functionalities: (a) way-points navigation and control which includes auto-landing (b) obstacle detection and avoidance, (c) fault detection and identification, and (d) system reconfiguration in two levels (high level and low level controllers). The resulting layered architecture is discussed in detail. More over the novel fault detection and identification method is developed to address multiplicative and additive faults. The testing environment for RUAV is developed to validate our architecture. Complete setup is carried out and run under QNX RTOS, based PC104 embedded board. The algorithms are tested and evaluated using HILS (Hardware-in-the-Loop simulation). Simulation result proves that the proposed architecture demonstrates desired efficiency and reliability.
    Full-text · Article · Nov 2012 · Journal of Aerospace Engineering
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    ABSTRACT: Cloud computing has emerged as a popular computing milieu that provides a range of delivering solutions for small to large enterprises with a flexible model that allows a computing power and storing space for the large volumetric data within minimum cost. These days, computational paradigm is shifting towards utility‐based pay‐as‐you‐go model and many discussion aside, but there remains no canonical definition of cloud computing yet. In this paper we have proposed a service‐oriented taxonomical spectrum of cloud computing, which is more focused on the service engineering perspective of cloud. Our argument behind cloud engineering is a layered structural approach ‘as a Service’ such as security as a service, fault tolerance as a service, architecture as a service. The main contribution of this paper is to identify a wide spectrum of taxonomy, aiming at a better understanding of functional as well as architectural components that could benefit from cloudification. We describe each sub‐taxonomy (architecture, core services, security, fault tolerance, management services etc.) in details. In addition, we present a comparative study of several cloud systems based on taxonomy. Moreover, it also identifies many challenges and opportunities that exist on the landscape of enterprise cloud. Copyright © 2011 John Wiley & Sons, Ltd.
    No preview · Article · Jun 2012 · International Journal of Communication Systems
  • S. Don · Eunmi Choi · Dugki Min
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    ABSTRACT: With the rapid development in IT enabled health care systems, the monitoring and diagnosis of patient have been replaced by embedded software systems. The limitations of these systems are interoperability and data aggregation across a wide range of devices. To solve these issues, the Medical Cyber Physical Systems (MCPS) has evolved as a new paradigm for health care systems, where the patients will have a flexible interaction with the cyber world in order to achieve an optimal decision result. In this paper we propose an architectural design framework for remote health care monitoring system. This framework is a dynamic event based sensing and monitoring system designed by integrating the full functionality of cyber physical system. The system adapts the concept of local and global awareness for intelligent decision making in physical and cyber world. A test scenario was considered to demonstrate the technical feasibility of the proposed system.
    No preview · Conference Paper · Jan 2012
  • Mino Ku · Eunmi Choi · Dugki Min
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    ABSTRACT: Virtualization technology is one of the key technology by explosive growth in several computing paradigm including cloud computing. Specially, some virtualization software stacks widely support virtualization mechanism on various types of system architectures despite some system architecture is not able to support hardware level virtualization. Thus the virtualization technique allows various systems to become a virtualized computing platform in virtualized computing environment. However, some virtualized systems generate the significant overhead by computation power during creation of the virtual hardware resources of the virtual machine. In our research, we analyze the creation overheads and characteristics of the virtual machine. To perform our study, we implement an automated measurement method and test bed which employs Xen as hypervisor on top of a cluster system with network storage server for distributing virtual disk images. Our experiments indicate that the creation of virtual machine generates significant overhead such as serious CPU utilization and context switches at initial phase for initiating virtual hardware resources of the virtual machine.
    No preview · Article · Aug 2011 · International Journal of Advancements in Computing Technology
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    Full-text · Chapter · Apr 2011
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    ABSTRACT: We propose a robot teleoperation service architecture that enables us to control robot more reliable. Reliability is one of key issues in the researches of network based robot architectures. Most of researches on robot architecture are to solve network related problems like latency or disconnection by implementing artificial intelligence at robots. In this paper, we explain 3-tier client-server network-based Robot Teleoperation Service Architecture. Users, who control the robot, can use any controllers and robots by this service architecture. Even if users are using two controllers and one robot, Kalman-based Signal Filter is reinforcing and separating these signals constantly. This kind of approach provides control that is more accurate and the result of test systems proves the proposed architecture reliability.
    No preview · Article · Jan 2011
  • Yunjung Park · Duckwon Chung · Dugki Min · Eunmi Choi

    No preview · Conference Paper · Jan 2011
  • N.M.K. Varma · Dugki Min · Eunmi Choi
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    ABSTRACT: In the current trend Virtual Machine Monitors (VMMs) are used as software-based solutions in the enterprise environments for building shared hardware infrastructures via virtualization. Proper utilization of the computer resources is one of the main goals of VMM. Xen is widely used VMM. The main aim of this paper is to diagnose the CPU utilization with different scenarios using the Xen VMM. This paper explains about three kinds of scenarios to diagnose the CPU utilization in Xen virtual machine environment. First scenario is to run the homogeneous virtual machines (VMs) with same memory allocation. In this scenario CPU utilization is diagnosed by adding number of homogeneous VMs to the Xen VMM with equal memory allocation to each VM. Second scenario is to run the homogeneous VMs with different memory allocation. CPU utilization is diagnosed in the second scenario by adding number of homogeneous VMs to the Xen with different sizes of memory allocation to each VM. In the third scenario CPU utilization is diagnosed by running maximum number of homogeneous VMs with same memory allocation in different memory configured systems.
    No preview · Conference Paper · Jan 2011
  • Mino Ku · Dugki Min · Eunmi Choi
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    ABSTRACT: Virtualization technology is one of the key technology by explosive growth in several computing paradigm including cloud computing. Specially, some virtualization software stacks widely support virtualization mechanism on various system types including a system which doesn't support hardware level virtual- ization. Thus the virtualization technique allows various systems to become a computing platform in virtualized computing envi- ronment. However, some virtualized systems create critical utili- zation by computation power during creation of virtual machine. In our research, we analyze creation characteristics of virtual machine on various dimensions like virtual machine, virtualized system, and storage server. To perform our study, we implement an automated measurement method and test bed which employs Xen as hypervisor on top of the cluster systems with storage serv- er for distributing virtual disk images. Our experiments indicate that computational power of virtualized system affects the boot time of virtual machine in our test bed even the heterogeneity is relatively row. Also, the creation of virtual machine creates sig- nificant overhead (100%) at initial phase on virtualized system in worst case. Additionally, we provide overhead analysis on storage server through generating workloads by scaling virtual machines.
    No preview · Article · Jan 2011
  • Vishnu Kumar · Hanmaro Yong · Dugki Min · Eunmi Choi
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    ABSTRACT: Autonomous landing is a challenging and important task for rotorcraft-based unmanned aerial vehicle (RUAV). This paper presents an autonomous landing algorithm for RUAV. The accurate landing is achieved by generating reference trajectory using near-minimum-time maneuver method and tracked with Lyapunov stabilizing approach. Along with this the testing environment for RUAV is developed to validate our landing algorithm. Complete setup is implemented and run under QNX RTOS, based on PC104 embedded board. The algorithm is tested and evaluated using HILS (Hardware in the loop simulation). Simulation result shows that proposed algorithm effectively handles elevated terrain under high altitude and lands accurately.
    No preview · Article · Nov 2010
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    ABSTRACT: This paper is about one more method for the hand gesture recognition algorithms. Described system in this paper doesn't require wearing any device or gloves for the subject's hand. For detecting hand motion, simple stereo camera is needed. The actual difference of suggested method in this paper with previous works is we are using grayscale histogram to define depth threshold of calculated disparity map.
    No preview · Article · Oct 2010
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    ABSTRACT: Efficient traffic control systems are required in towns and cities around the world. As the number of vehicles increase, and new infrastructure is less viable; high levels of mobility become essential. This work proposes a strategy for Intelligent Transportation Systems (ITS), in particular for the task of adaptive signal management. This approach is based on Complex Event Processing (CEP). Event processing provides fast assessment of the situation, due to its inherent capabilities for pattern detection and information composition. This work proposes an architectural model based on the concept of event processing networks. Our model is specifically designed to derive events obtained from loop detectors and compose enhanced signal timings, representing accurately the requirements of the roadway for signal management.
    No preview · Conference Paper · Sep 2010
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    ABSTRACT: This paper proposes a classification method based on Complex Event Processing (CEP) for mammogram images. For breast cancer detection and early prevention, several factors must be considered. Mammogram is important and effective in breast cancer diagnosis. The Radiologist must analyze visually, based on his expertise, to determine whether it is cancer or not. We explore the use of CEP for breast cancer image classification and information enrichment. The results reveal that the application of event processing techniques improves the classification of images in the medical domain. The proposed system performs efficiently and timed-lined to help the Radiologist to make a more accurate assessment.
    No preview · Conference Paper · Jun 2010
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    ABSTRACT: This paper is to survey video encryption algorithms field which becomes as an important field nowadays. As an increasing rate of applying video is getting high, the security of video data becomes more important. In this paper listed several famous encryption schemes which have their own advantages and cryptographic stability. Three main classes of video encryption techniques are studied. Given encryption which based on entropy coding, reason is entropy coding based encryption solutions are regarded as one of the bests.
    Full-text · Conference Paper · Jun 2010
  • Vishnu Kumar · Yunjung Park · Dugki Min · Eunmi Choi
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    ABSTRACT: Secure data transmission and data routing are critical in designing cluster based sensor network. This paper presents a secure energy efficient dynamic routing scheme (SEEDR) for wireless sensor networks. SEEDR uses a symmetric cryptography algorithm to support security. The dynamic key exchange protocol based on DH (Diffie-Hellman) algorithm is proposed, with non blocking OVSF codes. Our analytical model and the security analysis prove that SEEDR increase data communication security and consume less communication energy.
    No preview · Article · Jan 2010
  • Bhaskar Prasad Rimal · Eunmi Choi
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    ABSTRACT: Cloud computing has emerged as a popular computing model to support processing volumetric data using clusters of commodity computers. Nowadays computational world is opting for pay-for-use models and hype and discussion aside, there remains no canonical definition of cloud computing. In this paper we proposed a wide spectrum of taxonomy for cloud computing, aiming at a better understanding of the categories of applications that could benefit from cloudification and that will address the landscape of enterprise IT, management services, and data governance etc.
    No preview · Conference Paper · Jan 2010

Publication Stats

625 Citations
12.89 Total Impact Points

Institutions

  • 2004-2014
    • Kookmin University
      • School of Management Information Systems
      Sŏul, Seoul, South Korea
    • Handong Global University
      Geijitsu, North Gyeongsang, South Korea
  • 1999-2010
    • Konkuk University
      • Division of Computer Science and Engineering
      Seoul, Seoul, South Korea
  • 1995-1996
    • Michigan State University
      • Department of Computer Science and Engineering
      East Lansing, MI, United States