|
| |
|
|
|
Chang-Won Park
Professor
Ph.D., 1985, Stanford University (1988)
Polymer rheology and processing
Plastic optical fibers (POF)
Chemical Mechanical Polishing
Micro-reformer for portable PEMFC
Interfacial phenomena in multiphase flows
|
Brief Description of Current Research
Multicomponent flows of polymeric materials are encountered frequently in
various industrial applications. Due to the complexity of polymer rheology,
numerous issues involving such flows remain to be understood. Our efforts in
this area focus on investigating various multicomponent flows of polymeric
fluids through an interplay between process modeling and experiment. Modeling
work is aimed at establishing theoretical bases of various fluid mechanical
behaviors observed experimentally. Fundamental understanding is thereby obtained
regarding the influence of polymer rheology and processing conditions on the
solid-state properties of various articles fabricated by such flows. This study
not only provides useful information for process improvement, but also
contributes to developing novel processing techniques for polymeric fluids. As
a specific application, various methods to fabricate graded index plastic
optical fibers (GI-POF) are investigated. GI-POF is currently of great interest
as a high bandwidth data transmission media for local area networks or home
networks.
Chemical mechanical polishing (CMP) is widely used for global planarization
of multilevel interconnects in microelectronics industry. In a typical CMP
process, a rotating wafer is pressed against a rotating polishing pad in the
presence of a slurry. Although it is well recognized that many variables such
as the applied normal force, relative velocity of wafer relative to the pad, pad
properties and slurry characteristics, have profound influences on the general
effectiveness of the CMP process, the current level of understanding is mostly
based on empiricism. Our modeling effort seeks to delineate the influence of
these variables at a fundamental level, thus providing guidelines for the
improvement of pad and slurry design.
Polymer electrolyte membrane fuel cells (PEMFC) offer very high power density
compared to other types of fuel cells. Furthermore, the intrinsic properties of
the materials used for PEMFCs make them to operate at a low temperature, thereby
allowing quick start-up and rapid load-response. Due to these advantages,
PEMFCs are favored as a portable power source for applications such as aviation,
automobile as well as consumer electronics (laptops, cell phones, camcorders,
etc.). Although pure hydrogen is the best fuel for PEMFC, difficulties
associated with hydrogen storage and the portability of the storage system make
hydrocarbons to be more practical choices as a fuel for small-size mobile
applications. Our research in this area seeks to develop a new design for a
micro-reformer to produce hydrogen from hydrocarbon fuels that provides high
efficiency in terms of conversion and thermal management, compactness, and easy
integration with the fuel cell for portability.
The presence of surface-active substances in multiphase flow systems results
in various perplexing interfacial phenomena. Fundamental understanding of such
phenomena is of technological importance, and our research group is tackling the
flows involving the motion of bubbles and drops under the influence of
surface-active substances.
Major Equipment
- Brabender and Killion extruders with die attachments for coextrusion
- Nicolet 5l0P FTlR
Selected Publications
- “Fabrication Techniques for Plastic Optical Fibers,” in Polymer
Optical Fibers, Nalwa, ed., C.-W. Park, American Scientific Publishers
(2004).
- A Chemical Mechanical Polishing Model Incorporating both the Chemcial
And Mechanical Effects,” K. Qin, B. Moudgil and C.-W. Park, Thin Solid
Films, Vol. 446, 277-286 (2004).
- Novel Method for the Fabrication of Gradient-Index Plastic Optical
Fibers,” In-Sung Sohn and C.-W. Park, AIChE J., Vol. 49, 2499 (2003).
- “Preparation of Graded-Index Plastic Optical Fibers by the
Diffusion-Assisted Coextrusion Process,” In-Sung Sohn and C.-W. Park,
Ind. & Eng. Chem. Research, Vol. 41, 2418 (2002).
- Homopolymer Physisorption: A Monte Carlo Study,” J. de Joannis, C.-W.
Park, J. Thomatos and I. A. Bitsanis, Langmuir, Vol. 17, 69 (2001).
- “Effective Medium Approximation and Deposition of Colloidal Particles in
Fibrous and Granular Media,” Li, Y. and Park, C.-W., Adv. Colloid
Interface Sci., Vol. 87, 1 (2000)
- “Stability of a two-layer blown film coextrusion,” K. S. Yoon and C.-W.
Park, J. Non-Newtonian Fluid Mech., Vol. 89, 97 (2000).
|
