• Hyuk Kyu Pak (박혁규)

  • Professor
  • Soft Matter and Biological Physics Experiment
  • Current Research Interests

    Liquid-solid/liquid/soft matter interfaces
    Any piece of matter in nature is bounded by a surface or interface. We study the dynamical phenomena near the interfaces between liquid and solid (or liquid, soft matter) in following aspects.

    (1) Understanding the principles and developing the devices of a micro power generator using the liquid droplet under oscillation
    (2) Understanding the charge distribution near the interfaces
    (3) Understanding the dynamics of micro particles near the interfaces
    (4) Measuring the biological membrane potential using the complex of quantum dots and soft matter

    Nonequilibrium fluctuations
    Most systems in nature are far from equilibrium. According to the second law of thermodynamics, the entropy of an isolated system should tend to increase until it reaches equilibrium. But according to recent studies about the nonequilibrium fluctuations, the second law is only a statistical one, and there is always nonzero possibility that the entropy of an isolated system might spontaneously decrease. As the size of the systems in interest becomes small, this unusual property becomes apparent.
    Currently we are studying the motion of a colloidal particles in an optical trap with a time-varying stiffness. This system can be compared with a heat engine which usually uses a piston to compress and decompress a macroscopic gas, for which temperature, volume and pressure are all well-defined. But our system is one particle gas driven out of equilibrium and the volume where the particle moves around id determined by the optical harmonic potential generated from an external laser light.

    His research interests include
    – Nonequilibrium Fluctuations (2010 – )
    – Biological physics (2002 – )
    – Micro-fluidics (2005 – )
    – Liquid thin films (1994 – )
    – Optical studies of complex fluids (1987 – )
    – Phase transitions and critical phenomena in the bulk and at the interfaces of liquids (1987 – )
    – Nonlinear dynamics and pattern formation in granular systems (1992 – 2003)
    – Nonlinear dynamical transitions at the onset of turbulence (1987 – 1991)
    – Nonlinear laser spectroscopy studies of organic molecules (1985 – 1987)

  • Biographical Sketch
    - B.S. in Physics (1985), Pusan National University, Busan, Korea
    - Ph.D. in Physics (1992), University of Pittsburgh, Pittsburgh, PA
    “Light Scattering Studies of the Transition Region of Weak Turbulence” Advisor: Prof. Walter I. Goldburg
    - Postdoctoral research associate in the Group of Prof. Robert P. Behringer
    - Department of Physics, Duke University, NC (1992-1994)
    - Postdoctoral research associate in the Group of Prof. Bruce M. Law
    - Department of Physics, Kansas State University, KS (1994-1995)
    Professor in Department of Physics, Pusan National University (1995 - 2014)
    Professor in Department of Physics, UNIST (2014 - )
    Member of IBS Center for Soft and Living Matter (2014 - )
  • Selected Publications
    - Nonequilibrium Fluctuations for a single-particle analog of gas in a soft wall Physical Review Letters (2015) 114, 060603
    - Breathing, crawling, budding, and splitting of a liquid droplet under laser heatings Soft Matter (2014) 10, 2679-2684
    - Electrical power generation by mechanically modulating electrical double layers Nature Communications (2013) (doi:10.1038/ncomms2485)
    - Diffusing-wave spectroscopy study of microscopic dynamics of three-dimensional granular systems Soft Matter (2010) 6, 2894-2900
    - Thermochemical control of oil droplet motion on a solid substrate Applied Physics Letters (2008) 93, 084102
    - Dynamics of prey-flock escaping behavior in response to predator's attack Journal of Theoretical Biology (2006) 240, 250-259
    - Coarsening Dynamics of Striped Patterns in Thin Granular Layers under Vertical Vibration Physical Review Letters (2002) 88, 204303
    - Capillary Force on Colloidal Particles in Freely Suspended Liquid Thin Film Physical Review Letters (2001) 86, 4326-4329