서울대 작용소 세미나 2003 May 2: 이상훈(성균관대/서울대); Gaps and bridges between hyponormality and subnormality 2005 Jul 8: 이상훈(Univ. of Iowa); Subnormal completion problem of two-variable weighted shifts 2006 Sep 15: 이상훈(서울대); Hyponormality and subnormality of multivariable weighted shifts I 2006 Sep 22: 이상훈(서울대); Hyponormality and subnormality of multivariable weighted shifts II 2007 Nov 9: 이상훈(충남대); Which hyponormal operators are subnormal?(어떤 아정규작용소가 부분정규인가?) 2008 Mar 28: 이상훈(충남대); On 2-variable subnormal completion problem 2008 Oct 10: 이상훈(충남대); Which 2-hyponormal 2-variable weighted shifts are subnormal? 2009 May 29: 이상훈(충남대); Truncated moment problem and 2-variable subnormal completion problem 2013 Apr 26: 이상훈(충남대); Subnormality of 2-variable weighted shifts with diagonal core 2015 Oct 30: 이상훈(충남대); Recursiveness and propagation of 2-variable weighted shifts