From Joon's Homepage (joonahn)

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Education

• Ph.D. Candidate in Electrical Engineering -- Jan. 2006 ~ Current
  University of Southern California, Los Angeles, CA
  (Advisor: Prof. Bhaskar Krishnamachari)

• Master of Science in Electrical Engineering -- Aug. 2007
  University of Southern California, Los Angeles, CA

• Bachelor of Science in Electrical Engineering -- Feb. 2000
  Seoul National University, Seoul, Korea

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Research Experience

Graduate Research Assistant, Autonomous Networks Research Group, Department of Electrical Engineering, USC (Aug. 2005 ~ Current)

• Performance Analysis on Propagation Delay Tolerant ALOHA Protocol in Underwater Wireless Networks
  • Derived the throughput of the protocol for both finite and infinite number of nodes
  • Found and proved several analytical characteristics of the throughput
  • Developed approximate expressions for the maximum throughput and its maximizers
• Scaling Laws for Wireless Sensor Networks
  • Derived fundamental scaling laws for data-centric storage and querying in wireless sensor networks using a constrained optimization framework
  • Found that the scalability of a sensor network’s performance depends upon whether or not the increase in energy and storage resources with more nodes is outweighed by the concomitant application-specific increase in event and query loads
  • Found that 3D uniform deployments are inherently more scalable than 2D uniform deployments, which in turn are more scalable than 1D uniform deployments

• Data Replication Optimization in Wireless Sensor Networks
  • Considered the problem of optimizing the number of replicas for event information in wireless sensor networks when queries are disseminated using expanding rings
  • Found that event information should be replicated with a frequency that is proportional to the square root of their query rates to minimize the expected total energy cost consisting of search and replication costs, both with and without storage constraints

• Modeling Search Costs in Wireless Sensor Networks
  • Developed approximate closed-form expressions of expected minimum search energy costs for data-centric wireless sensor networks of various types

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Awards

• Best Student Paper Award by the USC Electrical Engineering-Systems Department, April 2006.

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Publications

• Joon Ahn and Bhaskar Krishnamachari, 'Scaling Laws for Data-Centric Storage and Querying in Wireless Sensor Networks', IEEE/ACM Transactions on Networking, 2008 (to appear)

• Joon Ahn and Bhaskar Krishnamachari, 'Performance of Propagation Delay Tolerant ALOHA Protocol for Underwater Wireless Networks', Intl Conference on Distributed Computing in Sensor Systems (DCOSS), Jun. 2008

• Joon Ahn and Bhaskar Krishnamachari, 'Performance of Propagation Delay Tolerant ALOHA Protocol for Underwater Wireless Networks', USC CENG Technical Report CENG-2007-13, Nov, 2007

• Joon Ahn and Bhaskar Krishnamachari, 'Modeling Search Costs in Wireless Sensor Networks', Workshop on Spatial Stochastic Models in Wireless Networks (SpaSWiN), April 2007

• Joon Ahn, Shyam Kapadia, Sundeep Pattem, Avinash Sridharan, Marco Zuniga, Jung-Hyun Jun, Chen Avin, Bhaskar Krishnamachari, 'Empirical Evaluation of Querying Mechanisms for Unstructured Wireless Sensor Networks', First International Workshop on Wireless Sensor Network Deployments, International Conference on Distributed Computing in Sensor Systems, 2007.

• Joon Ahn and Bhaskar Krishnamachari, 'Fundamental Scaling Laws for Energy-Efficient Storage and Querying in Wireless Sensor Networks', ACM MobiHoc, May 2006.

• Bhaskar Krishnamachari and Joon Ahn, 'Optimizing Data Replication for Expanding Ring-based Queries in Wireless Sensor Networks', WiOpt, April 2006.

• Joon Ahn and Bhaskar Krishnamachari, 'POSTER: Is Data-Centric Storage and Querying Scalable?', ACM Sensys, Oct. 2006

• Joon Ahn and Bhaskar Krishnamachari, 'Derivations of the Expected Energy Cost of Search and Replication in Wireless Sensor Networks', USC Computer Engineering Technical Report CENG-TR-2006-3, 2006.

• Bhaskar Krishnamachari and Joon Ahn, 'Optimizing Data Replication for Expanding Ring Queries in Wireless Sensor Networks', USC Computer Engineering Technical Report CENG-05-14, October 2005.

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Teaching Experiences

• Teaching Assistant of 'Probabilistic Methods in Computer Systems Modeling (EE465)', Electrical Engineering - Systems, University of Souther California, Spring 2006

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Industrial Experiences

• Internship, Trellisware Technologies, Inc., summer 2008

  Analyzed their cooperative path lifetime and investigated how to use the QualNet for evaluating their communication methods.

• Software Engineer, Digital & Digital Inc., Seoul, Korea, 2004

  Managed Embedded Linux kernel and contents encryption in HDD for Digital Video Recorder (DVR)

• Software Engineer, Digital & Digital Inc., Seoul, Korea, 2001 ~ 2002

  Developed SW for DVR including frameworks, database, user interfaces, hardware controller, etc.

• Software Engineer, Saint Media Co., Seoul, Korea, 2000 ~ 2001

  Developed the image processing applications for MS Windows

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Selected Graduate Courses

• Design and Analysis of Computer Communication Networks (EE 550) -- Ranked First
• Broadband Network Architecture (EE 555) -- Ranked First
• Probabilistic Methods in Computer Systems Modeling (EE 465) -- Ranked First
• Randomized Algorithm (CSCI 599)
• Analysis of Algorithms (CSCI 570)
• Fundamental Concepts of Analysis (MATH 425a)
• Computational Geometry (CSCI 583)

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Professional Activities

• Reviewer for Elsevier Computer Networks Journal Special Issue 2007, Computer Networks Journal, VTC2007, Special Issue on Wireless Sensor Networks for the Real-Time Systems Journal 2006