• HOME
  • >
  • 소식
  • >
  • 세미나
장소 B501, Room Red, KI bldg. 5nd fl. 
일시 2015/08/04, 11PM 
연사 Dr. Eric Jin Ser Lee(Univ. of Manitoba, Canada) 

Propagation of ultrasound through two- and three-dimensional strongly scattering media

2015/08/04(TUE), 11PM, B501(Room Red, KI bldg. 5nd fl.)
Dr. Eric Jin Ser Lee,  Department of Physics and Astronomy, Univ. of Manitoba, Canada



During my Ph. D study at the University of Manitoba, I have investigated the propagation of ultrasound through two- and three-dimensional strongly scattering media, with either random or ordered internal structures, through experiments and finite element simulations.  All media investigated have strong scattering resonances, leading to novel transport behaviour. 


The two-dimensional samples consist of nylon rods immersed in water.  Nylon fishing lines under tension are used as two-dimensional scatterers.  Note that since the rods are parallel and of uniform diameter, there is negligible scattering of waves out of the plane perpendicular to the rods, so that the system appears two-dimensional from the wave point of view for propagation in this plane.  When nylon rods are surrounded by water, they exhibit strong scattering resonances.  In such an environment, the nylon scattering resonance can couple with the propagating mode through water to create a bandgap.  This is a called hybridization gap.  When the nylon rods are arranged in a triangular lattice to form two-dimensional phononic crystals, very unusual dispersion properties are observed when the lattice constant is adjusted so that Bragg and hybridization gaps overlap in frequency.  This behaviour is attributed to the competition between two co-existing propagating modes, leading to a new method for tuning bandgap properties and adjusting the transmission by orders of magnitude. 


The three-dimensional media were fabricated by brazing aluminum beads together to form a disordered porous solid network with either vacuum in the pores.  This system is of particular interest because it has been shown to exhibit Anderson localization of ultrasound.  With such system, the density of states (DOS) was investigated.  It is the number of vibrational states per unit frequency range per unit volume.  The DOS is a fundamental property of any system and can influence not only wave transport but also the possibility of forming localized states.  The DOS was measured by directly counting the modes in the frequency domain.  At intermediate frequencies, the DOS was found to be approximately independent of frequency, while at higher frequencies, the frequency dependence was consistent with traditional DOS models.  Furthermore, the level statistics, which describe the distribution of the separations between neighbour modes in frequency, of the modes was investigated to determine the conditions under which level repulsion occurs.  As the sample becomes larger to have more modes, the modes start to overlap and repel each other so that level repulsion effects become important.  Consequently, the level statistics were observed to become closer to GOE predictions as the sample size increased.  For the last, as there is a transition from diffusive to localized regime around the lower bandgap edge, a transition from GOE to Poisson distribution is observed.


Contact: Prof. YongKeun Park, Physics Dept., (



번호 일시 장소 연사 제목
공지 2019/09/18 - 12/5  Seminar Room #1323  Prof. David Schuster and etc.  Fall 2019: Physics Seminar Serises
공지 2019/09/02 - 12/09  Seminar Room 1501  이호성 박사 (한국표준과학연구원) and etc.  Fall 2019: Physics Colloquium
284 5월 17일(화), 11:00 ~ 12:00  창의학습관(E11), 406호  방준혁 박사(Korea Basic Science Institute, KBSI)  The CERN Resonant WISP Search: Development, Results and Lesson-Learned
283 2013/09/09-12/09  E6, 1501  박혁규교수(부산대) 외  Physics Colloquium : 2013 Fall
282 April 6 (Fri.), 10:00 AM  #2502, E6  박채연 박사  Entanglement and thermalization in many-body systems: recent progress file
281 2015/09/15-12/08  E6, 1501  박제근 교수(서울대 물리학과) 외12명  Physics Colloquium : 2014 Fall file
280 2016/03/11-06/09  E6-2, 1501 외  박권(KAIS) 외  Physics Seminar Serises : 2016 Spring file
279 2015/09/07-12/01  E6, 1501  문은국 교수(KAIST) 외  Physics Colloquium : 2015 Fall file
278 2011/09/03-12/06  E6, 1501  김용균교수(한양대) 외  Physics Colloquium : 2011 Fall file
277 Oct. 10(Tue) 4PM  E6-2 #1323  김성웅 교수 (성균관대학교 에너지과학과)  Discovery of New 2D Materials with Diverse Physical Properties
276 2013/03/11-06/10  E6, 1501  강명수교수(KAIST) 외  Physics Colloquium : 2013 Spring
275 Jun. 14 (Tue) 4PM  Seminar Room (#2502, 2nd fl.)  Young-Sik Ra, Université Pierre et Marie Curie  Photonic quantum network based on multimode squeezed vacuums and single-photon subtraction
274 2012/04/02, 4PM  E6, 1501  Yong Hee Jeong  A new route to ferroelectricity in magnetic spinels: a case of Co2MnO4
273 2016/09/05-12/12 4PM  Natual Scien Bldg.(E6)m #1501  Yeong Kwan Kim 외  Physics Colloquium : 2016 Fall file
272 DEC. 26 (Wed), 04:00 PM  E6-1. 3rd fl. #3434  Y. Kim, A. Go, K. Hwang and E.-G. Moon  Informal Workshop on Topology and Correlation file
271 Sep. 14(Mon) 17:30~  Zoom webinar  Teruo Ono (Kyoto U. Japan)  KAIST Global Forum for Spin and Beyond (Third Forum) file
270 July 8(Mon), 14:00  E6, #1322  T. L. M. Guedes (Univ. of Konstanz)  Ultrabroadband squeezed pulses and their relation to relativity file
269 February 20 (Thu), 4:00 PM  #1323, E6-2  Seunghyun Khim  Unconventional superconductivity in the locally non-centrosymmetric heavy-fermion CeRh2As2 file
268 2016/09/29-12/13  E6-2, #1323  Sangyoon Han 외  2016 Fall, Physics Seminar Serises file
267 2015/07/16-07/17  E6-2, 1501  Sang-Wook Cheong (Rutgers Univ.)  KAIST Physics Distinguished Lecture
266 Nov. 28 (Tue.), 4:00 PM  #1323 (E6-2. 1st fl.)  Samindranath Mitra, Editor at Physical Review Letters  Physics after the lab and the desk: Your work in PRL file
265 Apr. 27, 2017 (Thu) 4:00 pm  Seminar Room(#1323, E6-2)  Prof.Donghan Lee (Chungnam National Univ.)  반도체 양자점을 이용한 단광자 광원