Past Projects

Missouri University of Science and Technology, Graduate Research Assistant, Jan. 2005 – Dec. 2011
• First to solve a disruption-tolerant routing problem via reinforcement learning by adaptively selecting link state or gossip routing schemes depending on the link availability of a network node, improving the packet delivery rate by up to 35%
• First to successfully train complex neural network architecture modified Cellular Simultaneous Recurrent Network (CSRN) with the proposed cellular Particle Swarm Optimization (PSO) algorithm for computer Go
• First to propose novel system architecture for human-computer interface of a robot that plays a game of Go and to implement a prototype Go robot with a robot arm
• Proposed a novel unsupervised learning algorithm, Collective Cooperative Learning
• Developed neural network simulators (CSRN & fuzzy ART) in C++, MATLAB, & scripting languages (Shell, AWK, Perl, Make) automated to run simulations and post-process results

• National Science Foundation (NSF) project on computer Go research (contract number ECCS-0725382)
• DARPA Disruption Tolerant Networking (DTN) Program (contract number W15P7T-05-C-P211), through a subcontract to BBN Technologies

Qualcomm, Intern, San Diego, CA, USA, Sep.–Dec.2007
• Added features to Qualcomm’s proprietary network simulator (netsim) in C++ for feedback-based adaptive rate control (H.263+; video stream/VoIP service) in 3G mobile networks (HSPA), leading to performance evaluation of the network
• Wrote utility program for netsim in Shell, AWK, Perl, and Make scripting languages to automate multiple simulations and post-processing of results; doubled the productivity in time

BBN Technologies, Intern, Cambridge, MA, USA, May–Aug. 2005
• First to model a problem that adaptively selects link state or gossip routing protocols in highly disruptive networks with Markov Decision Process (MDP)
• Developed an event-driven network simulator, ADPNetsim, in C++ as a key team member

University of Nebraska-Lincoln, Graduate Research Assistant, Aug. 2003 – Jul. 2004
• Researched pulse shaping for multi-band OFDM system

Siemens Mobile, Intern and Diplomarbeiter, Bocholt, NRW, Germany, Jul. 2001–Jun. 2002
• Proposed a medium access control (MAC) algorithm that enhances the overall throughput of wireless home networks (802.11a & 11e; L1 & L2) by 9% and provides QoS to multimedia traffic
• Researched cross-layer optimization between MAC and TCP layers for wireless multi-hop ad hoc networks that eventually led to the invention of Dynamic Offset Contention Window algorithm
• Modified NS-2 to comply with specifications (802.11a & 11e) in C++ & Tcl/Otcl and automated simulations/post-processing of the results in MATLAB, Shell, AWK, and Make scripting languages, correcting the incorrect timing issues of NS-2 Atheros package and increasing productivity in time

• Qualcomm Project on “a Scheduler for Real-time Multimedia Service in the Next Generation Wireless Transmission System”
• Qualcomm Project on “the Forward-link TCP/RLP Performance and Adaptive Error Control Method of Synchronous Multi-carrier CDMA and Asynchronous DS-CDMA System on Multiple Cell Environment”

Class Projects
Class Noise cancellation with least mean square (LMS) algorithm in MATLAB, Adaptive Signal Processing, UNL, Spring 2004
CMOS amplifier design with PSpice, Electronics II, Yonsei University, Fall 1998