ABOUT

Youngjun Joo, Ph. D.

Education

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Ph. D. in School of Electrical Engineering and Computer Science, Seoul National Univer- sity, Mar. 2008 – Aug. 2014. (Supervisors: Prof. Jin Heon Seo and Prof. Hyungbo Shim, http://cdsl.snu.ac.kr)

B.S. and M.S. in School of Electrical Engineering and Computer Science, Seoul National University, Mar. 1999 – Feb. 2005 and Mar. 2005 – Feb. 2007, respectively.

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Career

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Senior Research Fellow, LG Electronics, Sep. 2018 - present.

Postdoctoral Researcher in Systems & Control Lab., University of Central Florida, Jul. 2015 - Jul. 2018.

(Supervisor: Prof. Zhihua Qu, http://ece.ucf/edu/∼qu)

Postdoctoral Researcher in BioRobotics Lab., Hanyang University, Sep. 2014 - Jun. 2015.

(Supervisor: Prof. Youngjin Choi, http://biorobotics.hanyang.ac.kr)

Research Associate in Automation and Systems Research Institute, Seoul National Uni- versity, Sep. 2007 - Feb. 2008.

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Research Interests​

Control Theory

– Cybersecurity on Cyber-physical Systems
– String Stability on Autonomous Vehicle Platoon
– Consensus of Heterogeneous Uncertain Multi-Agent Systems
– Dissipativity Theory (passivity-short systems)
– Sampled-data Systems
– Disturbance Observer (nominal performance recovery for uncertain systems)

– Robust Control
– Nonlinear Control Theory (singular perturbation, high-gain observer)

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Applications

– Robot Manipulator (vibration suppression)
– Wind Power System (power and pitch control)
– Hard Disk Drive System (disturbance rejection)
– One-Legged Hopping Robot
– Autofocusing System for Mobile Phone (tracking control)

– Wide-area generation control

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Publications

International Journal:

• Robust stability of discrete-time disturbance observers for sampled-data systems: a fast sampling approach, Gyunghoon Park, Chanhwa Lee, Youngjun Joo, and Hyungbo Shim, Submitted to Automatica.

• Attack-aware control of cyber-physical system using nonlinear encoding under stealthy false data injection attack, Youngjun Joo, Zhihua Qu, Toru Namerikawa, Submitted to IEEE Transaction on Automatic Control.

• Preserving and achieving passivity-short property through discretization, Youngjun Joo, Roland Harvey, and Zhihua Qu, Submitted to IEEE Transactions on Automatic Control (2nd round).

• Recovering nominal tracking performance in an asymptotic sense: a disturbance observer approach with internal model, Gyunghoon Park, Hyungbo Shim, and Youngjun Joo, SIAM Journal on Control and Optimization, vol. 56, no. 2, pp. 700–722, 2018.

• Yet another tutorial of disturbance observer: robust stabilization and recovery of nominal performance, Hyungbo Shim, Gyunghoon Park, Youngjun Joo, Juhoon Back, and Nam H. Jo, Control Theory and Technology, vol. 14, no. 3, pp. 237–249, 2016.

• Embedding internal model in disturbance observer with robust stability, Youngjun Joo, Gyunghoon Park, Hyungbo Shim, and Juhoon Back, IEEE Transactions on Automatic Control, vol. 61, no. 10, pp. 3128–3133, 2016.

• Dynamic modeling and control of hopping robot in planar space, Seungbin Baek, Junho Park, Youngjun Joo, Jongguk Yim, and Youngjin Choi, Intelligent Service Robotics, vol. 9, no. 2, pp. 153–161, Apr. 2016.

• A study of disturbance observers with unknown relative degree of the plant, Nam H. Jo, Youngjun Joo, and Hyungbo Shim, Automatica, vol. 50, no. 6, pp. 1730–1734, Jun. 2014.

• Power regulation of variable speed wind turbines using pitch control based on disturbance observer, Youngjun Joo and Juhoon Back, Journal of Electrical Engineering & Technology, vol. 7, no. 2, pp. 273–280, Mar. 2012.

• Sliding mode controller for torque and pitch control of PMSG wind power systems, Sung-Hun Lee, Youngjun Joo, Juhoon Back, Jin-Heon Seo, and Ick Choy, Journal of Power Electronics, vol. 11, no. 3, pp. 342–349, May, 2011. ​​

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International Conference:

• Cooperative control of heterogeneous multi-agent systems in sampled-data setting, Youngjun Joo, Zhihua Qu, and Roland Harvey, The 55th IEEE Conference on Decision and Control, 2016.

• On robust stability of disturbance observer for sampled-data systems under fast sampling: an almost necessary and sufficient condition,

  Gyunghoon Park, Youngjun Joo, Chanhwa Lee, and Hyungbo Shim, The 54th IEEE Conference on Decision and Control, 2015.

• Asymptotic rejection of sinusoidal disturbances with recovered nominal transient perfor- mance for uncertain linear systems, Gyunghoon Park, Youngjun Joo, and Hyungbo Shim, The 53th IEEE Conference on Decision and Control, 2014.

• Reduced order type-k disturbance observer based on a generalized Q-filter design scheme, Youngjun Joo and Gyunghoon Park, The 14th International Conference on Control, Automation and Systems, 2014.

• A simple noise reduction disturbance observer and Q-filter design for internal stability, Jerome Han, Hongkeun Kim, Youngjun Joo, Nam Hoon Jo, and Jin Heon Seo, The 13th International Conference on Control, Automation and Systems, 2013.

• Analysis of discrete-time disturbance observer and a new Q-filter design using delay function, Chanhwa Lee, Youngjun Joo, and Hyungbo Shim, The 12th International Conference on Control, Automation and Systems, 2012.

• Rejection of polynomial-in-time disturbances via disturbance observer with guaranteed ro- bust stability, Gyunghoon Park, Youngjun Joo, Hyungbo Shim, and Juhoon Back, The 51th IEEE Conference on Decision and Control, 2012.

• A note on disturbance observer with unknown relative degree of the plant, Nam H. Jo, Youngjun Joo, Hyungbo Shim, and Young Ik Son, The 51th IEEE Conference on Decision and Control, 2012.

• Can a fast disturbance observer work under unmodeled actuators?, Nam H. Jo, Youngjun Joo, and Hyungbo Shim, The 11th International Conference on Control, Automation and Systems, 2011.

• Sliding mode controller for torque and pitch control of wind power system based on PMSG, Sung-Hun Lee, Youngjun Joo, Juhoon Back, and Jin-Heon Seo, The 10th International Conference on Control, Automation and Systems, 2010.

• Power and torque limitations of variable speed wind turbines using pitch control based on disturbance observer, Youngjun Joo, Juhoon Back, and Seung-Ho Song, The 16th International Conference on Electrical Engineering, 2010.

• An inner-loop controller guaranteeing robust transient performance for uncertain MIMO linear systems

  Juhoon Back, Hyungbo Shim, and Youngjun Joo, The 17th World Congress The International Federation of Automatic Control, 2008.

• State space analysis of disturbance observer and a robust stability condition, Hyungbo Shim and Youngjun Joo, The 46th IEEE Conference on Decision and Control, 2007. ​​