A Brief Summary on Re-search Activities

Cao, JunKorea University

Advisor: Prof. Wonjun Lee

2010.11.07

Contents

• Curriculum Vitae• Research Summary• Master Thesis• Other Projects• Conclusion

Curriculum Vitae

• Family Parents (Beijing, China)

• Education 2000.09 – 2003.07 Taiyuan No.5 School, Shanxi Province,

PRC2004.03 – 2005.02 Korean language course, Hongik Univer-sity2005.03 – 2009.02 B.S., Korea University

2009.03 – 2011.02 M.S., Korea University

• Internship2007.07 – 2009.02 Network Lab., Korea University2007.01 – 2007.02 SK Corporation2006.07 – 2006.08 SK Telecom

Curriculum Vitae

• Graduate InformationNetwork Lab. Department of Computer Science and En-gineeringAdvisor: Prof. Wonjun Lee

– Research topics• IEEE 802.11, WLAN• Wireless Mesh Network• Medium Access Control• Routing in Wireless Ad Hoc Network• Distributed Computing

– Master ThesisA simple Distributed Dynamic Set Scheme for Exposed Terminal Prob-

lems

Research Summary

• Projects2007.09 – 2009.02 ( 인턴 ) • Sponsor: ITRC-HCI, IITA ( 정보통신연구진흥원 )• Topic: Communication protocol for HCI applications

2009.03 – 2010.02 ( 석사 1 년 ) • Sponsor: KOSEF ( 한국과학재단 )• Topic: Topology control using cooperative communication

2010.03 – 2011.02 ( 석사 2 년 )• Sponsor: KRF ( 한국학술진흥원 )• Topic: Packet scheduling in relay assistant networks

1st Year, Internship

• Topic: Communication protocol for HCI applications• Activity: Wireless Mesh Network test-bed construction

• Setup Phase– Server

• Linux server edition

– Embedded router• Routing, Interface

– Analysis tools• Traffic generator• Traffic dumping

• Testing examples– Routing path selection– Handoff– Channel assignment

Wireless backbone 802.11aWired backbone (for administration purpose)

Master course 1st year

• Topic :Topology control using cooperative commu-nication

Cooperative comm. for coverage exten-

sion

Disconnected topology in wireless networks

ISSUE: How to select the minimal set of links while maximizing connectivity?

Master course 1st year

• Solution– Step 1: clustering and selecting headers– Step 2: greedy algorithm to add links until requirement is

reached

Master course 2nd year

• Topic: Packet Scheduling in Relay Assistant Net-works

Relay assistant networks

ISSUEHow to schedule relays in a balance way?

Solution• Each relay is assigned with a relaying proba-bility.

• The relaying probability is inverse propor-tional to its traffic load K.

• By setting the expect number of relaying to 1, each relay solve the equation to get R.

• Results

Master course 2nd year

Master Thesis

• Topic: Spatial reuse and exposed terminal problem

ISSUE 1How to identify exposed terminals in distributed way?

ISSUE 2How to deal with collision?

Master Thesis

• Solution– Issue 1: Identifying exposed nodes

Exposed nodes dynamically join a dynamic set– Issue 2: handling collision

Common time stamp for handling concurrent transmis-sion

1 2

Master Thesis

Master Thesis

Other Projects

• Query by humming– Course name: 미디어처리 (4 학년 )– 구성 : 3 명 (UI / Signal Processing / Data structure)

*그림인용 : http://people.csail.mit.edu/edmond/projects/musicdb/musicd-b.pdf

Other Projects

• User-rate prediction for movies– Recommendation system– Course name: Algorithm (4 학기 )– 구성 : 2 명

• 17700 movies with user rates• 4400 users

A movie

K Nearest Node clustering

Correlation of rates by common users of any two movie.

movie the torate suser' n correlatio normalized A moviefor rate predicated si'user

iuser by ratedseen arewhich neighborsnearest sA' movie

Other Projects

• Results: (Input file) Probe.txt

answer no matrix shrink matrix shrink

RMSE: 1.39235 RMSE: 1.29320

Conclusion

• Publications

• TAs