KAIST, KAIST Institute for Optical Science and Technology (Jointly Appointed) 

KAIST, Ultrafast Optics for Ultraprecision Group, Department of Mechanical Engineering [GROUP LINK] 

Research Associate Professor (March 2013 - August 2014) 

Research Assistant Professor (March 2010 - February 2013) 

Demonstrated a high-resolution broadband femtosecond LIDAR by sweeping the repetition rate of the femtosecond fiber laser referenced to the time/frequency standard. Also developed high power fiber femtosecond laser and extending its application fields to coherent EUV generation and material processing. Performance improvement of pre-developed optical ranging principles in terms of the precision, range, and speed was an additional concern. Detailed research subjects were as follows.

• • All-fiber phase-locked repetition rate sweeping spectroscopy for broadband high-resolution femtosecond LIDAR

  • High-precision time-of-flight measurement using fiber femtosecond laser

    • Repetition rate multiplication of the fiber femtosecond laser

    • High precision time-of-flight measurement in extended range using high repetition rate femtosecond pulses

  • Real-time absolute distance measurement using multi-channel optical frequency generator

    • Generation of multi-channel optical frequencies referenced to the fiber frequency comb

    • Optimal selection of the set of wavelengths for the absolute distance measurement

    • Compact & long-term stable coherent EUV generation by using high power fiber based femtosecond laser

    • High-level stabilization (frequency and power) of femtosecond fiber lasers

Quantum Electronics & Photonics Division, Physical Measurement Laboratory [GROUP LINK]

National Institute of Standards and Technology (NIST), Boulder CO, USA

NIST Guest Researcher (August 2011 - August 2013)           Advisor: Dr. Nathan R Newbury

Focused on combining two novel concepts of absolute measurement using ultrafast femtosecond pulses for diverse scientific and industrial applications: Multi-heterodyne (NIST) and balanced optical cross-correlation (KAIST). Applications include precise strain sensing, ultra-high-speed topography/tomography, and absolute ranging of multiple target objects.

KAIST, Ultrafast Optics for Ultraprecision Engineering Research Group [GROUP LINK]

Postdoctoral Associate (September 2008 - February 2010)    Advisor: Prof. Seung-Woo KIM

Developed the principle of high -precision optical ranging using time-of-flight of femtosecond pulses especially for space missions based on formation-flying of several satellites. Also demonstrated the optical frequency generator with compactness and high reliability based on the optical injection locking of the fiber frequency comb and applied them to the absolute distance metrology and DWDM telecommunications. Another concern was the construction of the high power fiber-based femtosecond laser. Detailed research subjects are as follows. 

• • High precision time-of-flight measurement using fiber-based femtosecond laser

    • Nanometer precision optical ranging based on balanced optical cross-correlation 

  • Absolute distance measurement using long-term stable all-fiber optical frequency generator

    • Long-term reliable optical frequency generation referenced to the optical comb 

  • Compact & long-term stable high power femtosecond Yb-fiber laser

    • Linewidth narrowing of the fiber femtosecond laser by noise suppression

    • Development of long-term stable seed source for high power fs Yb fiber amplifiers

KAIST, Billionth Uncertainty Precision Engineering Research Group [GROUP LINK]

Research Assistant (March 2002 - August 2008)    Advisor: Prof. Seung-Woo KIM

• • Developed novel precise light sources referenced to the time/frequency standards with utmost precision and applied them to various kinds of absolute distance measurement technologies.

  • Absolute Distance Measurement by using the Optical Frequency Generator:

    • Demonstrated measurement uncertainty of 17 nm with an absolute distance of 1 meter. The performance would be enhanced to sub pm level in a vacuum like space environment where the uncertainty caused by the air doesn’t matter.

  • Optical Frequency Generators (OFG):

    • Developed novel light source referenced to the time/frequency standards especially with wide tunable range, moderate power sufficient for most applications and single frequency characteristics. The resulting frequency uncertainty of the OFG has reached to 10-12 level. And it is also demonstrated 10-15 uncertainty can be obtained with the advent of the reference time/frequency standard in use.

  • Optical Frequency Comb: Full Stabilization of the Mode-locked Femtosecond Laser:

    • Constructed the optical frequency comb centering at 800 nm using mode-locked Ti:Sapphire laser. The two degree of freedom of the whole optical modes in the optical frequency comb, the repetition rate, and the carrier envelope offset frequency is measured by the self-referencing f-2f interferometer and stabilized to the Rubidium atomic clock. The stability faithfully followed that of the reference clock (below 10-12). Digital phase locked loop was designed for the stable locking with wide dynamic ranges.

  • Volumetric Interferometer using Heterodyne Technique:

    • Developed a positioning sensor capable of determining three-dimensional coordinate directly without reconstruction of Cartesian coordinate from three separate information from each x-, y- and z-axis. Adoption of the heterodyne technique made it possible to enhance the measurement speed and lower the errors due to the intensity variation, which has limited the performance of the precedent volumetric interferometry.

  • Retrofit of the 3 Dimensional Coordinate Measuring Machine (CMM):

    • Retrofitted optical scales, guide-way and controller of the CMM and operated as an assistant.

AIST- National Metrology Institute of Japan (NMIJ),

Lengths and Dimensions Division, Length Standards Section (Tsukuba, JAPAN)

Visiting Researcher (January 2005 - February 2005)

• • Fabry-Perot based Displacement Measurement with pm Resolution

  • Tunable CW Laser Referenced to the Optical Comb for Precise Displacement Metrology

  • Worked with Dr. Kaoru Minoshima and Dr. Thomas. R. Schibli

ACADEMIC TRAINING

Korea Advanced Institute of Science & Technology (KAIST)    Daejeon, KOREA

Doctor of Philosophy in Mechanical Engineering, August 2008.  [Advisor: Prof. Seung-Woo KIM]

Thesis: Optical Frequency Generator for Absolute Distance Measurements based on the Optical Frequency Comb of a Femtosecond Pulse Laser

Korea Advanced Institute of Science & Technology (KAIST)    Daejeon, KOREA

Master of Science in Mechanical Engineering, February 2004.  [Advisor: Prof. Seung-Woo KIM]

Thesis: Volumetric Interferometer using Heterodyne Technique

Korea Advanced Institute of Science & Technology (KAIST)    Daejeon, KOREA

Bachelor of Science in Mechanical Engineering, February 2002.

PROFESSIONAL ACTIVITIES

• • Young Scientist Award (젊은과학자상), Korean President(대통령상), 2021. 

  • Optical Technology Innovation Award (광기술혁신상), Optical Society of Korea, 2021.

  • Outstanding Presenter Award, International Symposium on Precision Engineering and Sustainable Manufacturing (PRESM) 2020.

  • IJPEM-Green Technology Highly Commended Paper Award, The Korean Society of Precision Engineering 2019.

  • Outstanding Presenter Award, International Symposium on Precision Engineering and Sustainable Manufacturing (PRESM) 2020.

  • Outstanding Presenter Award, International Symposium on Precision Engineering and Sustainable Manufacturing (PRESM) 2019.

  • Young Researcher Award, International Symposium on Precision Engineering and Sustainable Manufacturing (PRESM) 2018.

  • 1st Prize for KAIST EEWS Business Planning Competition, 2010, KAIST, DFJ Athena LLC (Venture Capital), and Il-shin Venture Capital (EEWS: Energy, Environment, Water, and Sustainability)

  • Singapore National Research Foundation (NRF) Fellow, 3,000,000 SGD, 2015-2020 (funded by the National Research Foundation of Singapore).

  • elite Nanyang Assistant Professorship (NAP), 1,000,000 SGD (funded by Nanyang Technological University (NTU), Singapore), 2014.

  • Best Paper Award, Asian Society of Precision Engineering and Nanotechnology (ASPEN), 2019

  • Best Paper Award, Asian Society of Precision Engineering and Nanotechnology (ASPEN), 2013

  • Best Paper Award, Optical Society of Korea (OSK), 2021 (Two times)

  • Best Paper Award, Optical Society of Korea (OSK), 2016

  • Best Paper Award, Optical Society of Korea (OSK), 2014

  • Best Paper Award, Korean Society of Precision Engineering (KSPE), 2021 (Three times)

  • Best Paper Award, Korean Society of Precision Engineering (KSPE), 2016

  • Best Paper Award, Korean Society of Precision Engineering (KSPE), 2014

  • Best Paper Award, Korean Society of Precision Engineering (KSPE), 2011

  • Associate Member (정규회원, 전체 130명) of CIRP (The International Academy for Production Engineering).

  • Member of Y-KAST (Young Korean Academy of Science and Technology).

  • Editorial Director (편집이사, 적층제조 부문이사) of Korean Society of Precision Engineering (KSPE).

  • Editorial Director (생산/설계부문 편집이사, 나노/마이크로부문 편집이사, 적층제조연구회 총무간사) of Korean Society of Mechanical Engineers (KSME).

  • Editorial Board Member of Virtual and Physical Prototyping published by Taylor & Francis (Impact Factor: 10.60).

  • Editorial Board Member of International Journal of Precision Engineering and Manufacturing (IJPEM) published by Korean Society of Precision Engineering (KSPE) (Impact Factor: 1.378).

  • Topical Editor of Current Optics and Photonics (COPP) published by Optical Society of Korea (OSK) (Impact Factor: 0.660).

  • Guest Editor of ‘Sensors’ (Impact Factor: 3.275)

  • Guest Editor of ‘Photonics’ (Impact Factor: 2.140)

  • Guest Editor of ‘Micromachines’ (Impact Factor: 2.523)

  • Director of Academic Affairs of ‘Korean Scientists and Engineers Association in Singapore (KSEASG)’ 2018-2019.

  • Councilor of ‘Korean Scientists and Engineers Association in Singapore (KSEASG)’, 2018-2019.

  • International Scientific Committee of International Conference of Additive Manufacturing for a Better World 2022

  • Publication Committee of International Symposium on Precision Engineering and Sustainable Manufacturing (PRESM) 2022.

  • Organizing Chair of KAIST ME e-Symposium on Nano-Micro Sensing and Photonics 2021, 2021.

  • Program Chair of KAIST ME e-Symposium on Nano-Micro Sensing and Photonics 2020, 2020.

  • Organizing Committee of AKC 2019 (Asia Korea Conference on Science and Technology) organized by KOSFT (The Korean Federation of Science and Technology).

  • Technical Committee Chair of AKC 2017 (Asia Korea Conference on Science and Technology) organized by KOSFT (The Korean Federation of Science and Technology).

  • Technical Chair of icOPEN 2017 (International Conference on Optical and Photonic Engineering) organized by OPSS, A*STAR and SPIE.

  • Technical Chair of icOPEN 2015 organized by OPSS, A*STAR and SPIE.

  • Organizing Committee of International Symposium on Precision Engineering and Sustainable Manufacturing (PRESM) 2021.

  • Organizing Committee of International Symposium on Precision Engineering and Sustainable Manufacturing (PRESM) 2020.

  • Program Committee of the Optical Metrology Session in CLEO-PR 2022 (Conference on Lasers, Electro-Optics, Quantum Electronics and Laser Science Conference-Pacific Rim) organized by OSA (Optical Society of America).

  • Program Committee of the CLEO-PR 2020 (International Conference on Lasers and Electro-Optics) organized by OSA (Optical Society of America).

  • Program Committee of the CLEO 2014 (International Conference on Lasers and Electro-Optics) organized by OSA (Optical Society of America).

  • Program Committee of the CLEO 2013 (International Conference on Lasers and Electro-Optics) organized by OSA (Optical Society of America).

  • Program Committee of the CLEO 2012 (International Conference on Lasers and Electro-Optics) organized by OSA (Optical Society of America).

  • Program Committee of the PHOTOPTICS 2020 (International Conference on Photonics, Optics and Laser Technology).

  • Program Committee of the PHOTOPTICS 2019 (International Conference on Photonics, Optics and Laser Technology).

  • Program Committee of the PHOTOPTICS 2018 (International Conference on Photonics, Optics and Laser Technology).

  • Program Committee of the PHOTOPTICS 2017 (International Conference on Photonics, Optics and Laser Technology).

  • Program Committee of the PHOTOPTICS 2016 (International Conference on Photonics, Optics and Laser Technology).

  • Program Committee of the PHOTOPTICS 2015 (International Conference on Photonics, Optics and Laser Technology).

  • Program Committee of the PHOTOPTICS 2014 (International Conference on Photonics, Optics and Laser Technology).

  • Program Committee of the PHOTOPTICS 2013 (International Conference on Photonics, Optics and Laser Technology).

  • Program Committee of the ALPS 2018 (Advanced Laser and Photon Sources).

  • Conference Executive Committee of ICPT 2010 (International Conference on Positioning Technology)

  • Local Organizing Committee of ISMTII 2011 (International Symposium on Measurement Technology and Intelligent Instruments)

  • Session Chairs at CLEO, CLEO-PR, ICPT and other international conferences.

  • Member of OSA, SPIE, OSK, EUSPEN and KSPE.

  • (OSA: Optical Society of America, SPIE: International society for optics and photonics,

  • OSK: Optical Society of Korea, EUSPEN: European Society for Precision Engineering and Nanotechnology, KSPE: Korean Society of Precision Engineering)

  • Reviewer of Nature Photonics, Nature Communications, Light: Science & Applications, and Scientific Reports (NPG)

  • Reviewer of Optica, Optics Letters, Optics Express, JOSA B, and Applied Optics (OSA)

  • Reviewer of Advanced Materials Interfaces (Wiley)

  • Reviewer of ACS Advanced Materials and Interfaces (ACS)

  • Reviewer of IEEE Photonics Technology Letters

  • Reviewer of Measurement Science and Technology

  • Reviewer of Review of Scientific Instruments

  • Reviewer of International Journal of Precision Engineering and Manufacturing

  • Reviewer of Journal of Optics Communications

  • Reviewer of Optics and Lasers in Engineering

  • Reviewer of Optics and Laser Technology

  • Reviewer of RSC Advances (Royal Society of Chemistry)

  • Reviewer of Journal of Biomedical Optics (SPIE)

  • Reviewer of IEEE Chemical Physics Letters

  • Reviewer of IEEE Transactions on Terahertz Science and Technology

  • Reviewer of Journal of Engineering Manufacture

  • Reviewer of Journal of Testing and Evaluation

  • Reviewer of Jean Bennet Memorial Travel Grant Program (OSA)

  • Reviewer of Newport Travel Grant Program (OSA)

  • Reviewer of Journal of OSK (OSK)

GRANT WRITING EXPERIENCE (ACCEPTED)

• • Ultraprecision Photonics based on Femtosecond Lasers: National Honour Scientist Project sponsored by Korean Ministry of Education, Science and Technology: 2012 - 2022.

  • (Principal Investigator) Development of High-resolution LIDAR for Satellite Payload Project sponsored by Korean Ministry of Education, Science and Technology: 2011 - 2016.

  • (Principal Investigator) Stabilization of Femtosecond Fiber Lasers for Ultrafast Optics Project sponsored by Korean Ministry of Education, Science and Technology: September 2010 - 2013

  • (Principal Investigator) Global Network Research Program with NIST: Femtosecond Active LIDAR for Space Missions sponsored by Korean Ministry of Education, Science and Technology: 2011 - 2014

  • Ultrafast Femtosecond Laser based Ultraprecision Measurement, Inspection and Spectroscopy Project sponsored by Korean Ministry of Education, Science and Technology: January 2010 - Present

  • Coherent Optical Metrology based on full spectral Bandwidth (COMB) Project sponsored by Korean Ministry of Education, Science and Technology (Creative Research Initiative): June 2008 - Present

  • Distance Measurement and Spectroscopy based on Femtosecond Laser for Earth Observation and Planetary Exploration Project sponsored by Korean Ministry of Education, Science and Technology: July 2008 - Present

  • Billionth Uncertainty Precision Engineering (BUPE) Project sponsored by Korean Ministry of Science and Technology (Creative Research Initiative): March 2002 - May 2008

  • Measurement and Inspection of Complex Patterns on Products of Large Area Project sponsored by Korean Ministry of Knowledge Economy: October 2007 - September 2010

  • Consulting about Measurement/Inspection Process and System of the Shipbuilding Industry (Samsung Heavy Industry): 2004

  • Proposition of the Roadmap for the Shipbuilding Industry (Daewoo Shipbuilding & Marine Engineering): 2007 - 2008

LECTURES

• • KAIST, Department of Mechanical Engineering             South Korea

Professor (September 2019 – present)

• • • [ME600] Metrology (2020 Autumn), Korea Advanced Institute of Science and Technology (KAIST)

    • [ME251] Dynamics (2020 Autumn), Korea Advanced Institute of Science and Technology (KAIST)

    • [ME200] Basic Mechanical Practice (2020 Spring), Korea Advanced Institute of Science and Technology (KAIST)

    • [ME251] Dynamics (2019 Autumn), Korea Advanced Institute of Science and Technology (KAIST)

• • NTU, School of Mechanical and Aerospace Engineering               Singapore

Professor (September 2014 – present)

• • • [M6301] Advanced Metrology and Sensing Systems (2018 Spring), Nanyang Technological University (NTU)

    • [MA2001] Mechanics of Materials (2017 Autumn), NTU

    • [MA9032] Standards and Lasers in 3D Printing (2018 Summer), NTU

    • [MA9032] Standards and Lasers in 3D Printing (2017 Summer), NTU

    • [M6816] Laser Assisted Manufacturing (2018 Spring), NTU

    • [M6816] Laser Assisted Manufacturing (2017 Spring), NTU

    • [M6816] Laser Assisted Manufacturing (2016 Spring), NTU

    • [M6816] Laser Assisted Manufacturing (2015 Spring), NTU

    • [MA4842] Engineering Metrology (2017 Autumn), NTU

    • [MA4842] Engineering Metrology (2017 Spring), NTU

    • [MA4842] Engineering Metrology (2016 Autumn), NTU

    • [MA4842] Engineering Metrology (2016 Spring), NTU

    • [MA4842] Engineering Metrology (2015 Autumn), NTU

    • [MA4842] Engineering Metrology (2015 Spring), NTU