1. 제목 : Femtosecond Laser Processing and Characterization of Thermal Properties

2.연사 : Tae Y. Choi Ph.D., Assistant Professor, Department of Mechanical and Energy

          Engineering, University of North Texas

3. 일시 : 2012년 5월 14일 (월) 16:30 p.m.

4. 장소 : 301동 1409-1호 세미나실

5. 내용 : Femtosecond laser is a great tool for precision machining and other scientific experiments on thermal and optical characterization. I would like to introduce two approaches in small scale processing and characterization of various material systems including metals, nanowires, nanotubes, and graphene. The first approach is related to micro- and nano-manufacturing of a measurement platform to characterize thermal and optical properties of zero-, one- and two-dimensional nanosystems such as quantum dots with metal nanoparticles, nanowires and graphene. This approach focuses on micropipette-based thermal sensing and pump-and-probe sensing of optical signals to analyze coherent phonon oscillation in the nanosystems. To this end, a microfabricated device sensor can be subsequently tailored by focused ion beam (FIB) will be used. In the second approach, we have demonstrated a novel technology to obtain few-layers of graphene through a mechanical exfoliation method. Also, graphene patterning using a femtosecond laser pulse will be introduced. This technology originally demonstrated inside the vacuum chamber (in Dual FIB) is currently being developed in an open-air environment, which shows a great potential in top-down scalable nanomanufacturing of high-quality graphene. As compared to femtosecond laser characterization, this application will use higher intensity laser beam to remove thin layer of films.

6. 약력 : Dr. Tae Y. Choi joined University of North Texas in Fall 2006 as a founding junior faculty in the Department of Mechanical and Energy Engineering. After he earned his Ph.D. degree from University of California, Berkeley in 2002, he received his post-doctoral training at ETH Zurich, Switzerland. Soon after, he served as a lecturer for two and a half years at ETH before he came to UNT. He taught conventional and advanced mechanical engineering courses in the areas of thermal science and nanoscale energy transport. He conducted his research in small scale manufacturing and instrumentation such as characterization of micro and nanoscale thermal properties. He made significant contributions to scientific and engineering societies including American Society of Mechanical Engineers (ASME). He is an active member of ASME since 2007 while he has served in the ASME K-15 committee.

In the newly founded MEE department, research has been a challenging one since his service at UNT because of heavy time commitment in teaching, committee activities and other service opportunities, e.g., ABET committee. Furthermore, his research lab was not ready until Feb 2008. To make the situation worse, the department chair left UNT in the summer 2007 (one year after his service). Since then, MEE department has had three interim department chairs outside the department for almost three years. There have been only four non-tenured junior faculty members in the MEE department until UNT hired a new department chair in Sep 2010. Because of small number of faculty and large pool of undergraduate students (>200 students since 2008 and currently ~350 students), he had to teach two new courses every year by end of 2009, which implies that he has developed six new undergraduate and graduate courses. The following highlights summarize his major contributions at UNT in teacher-scholar activities for the last five years.

※ 문의 : 기계항공공학부  서갑양 교수 (880-9103)