## Talks

1. Milnor’s question on transfinite invariants, Knotted Embeddings in Dimensions 3 and 4, February 15, 2018, CIRM, Marseille, France.
2. Milnor’s transfinite invariant problem for 3-manifolds, The 13th East Asian School of Knots and Related Topics, January 31, 2018, Daejeon, Korea.
3. $L^2$-acyclic bordism and knot concordance, December 19, 2017, University of Regensburg, Regensburg, Germany.
4. Transfinite Milnor invariants of 3-manifolds, December 8, 2017, University of Warsaw, Warsaw, Poland.
5. Transfinite Milnor invariants of 3-manifolds, December 4, 2017, Max Planck Institute for Mathematics, Bonn, Germany.
6. 4-dimensional $L^2$-acyclic bordism of 3-manifolds, November 21, 2017, University Paris Diderot (Paris 7), Paris, France.
7. Cheeger-Gromov $L^2$ rho-invariants and low dimensional topology, MFO workshop: Interactions between Low-dimensional Topology and Complex Algebraic Geometry, October 23, 2017, Oberwolfach, Germany.
8. Milnor invariants and rational Whitney towers, September 25, 2017, St. Petersburg State University, St. Petersburg, Russia.
9. Hirzebruch-type invariants of Cheeger-Gromov and low dimensional topology, Oberseminar at Max Planck Institute for Mathematics, August 31, 2017, Bonn, Germany.
10. Bordism, chain homotopy, and Cheeger-Gromov $\rho$-invariants, Quantitative Geometry and Topology — a special session in Mathematical Congress of America 2017, July 25, 2017, Montreal, Canada.
11. 다양체의 위상수학과 디스크 임베딩 (Topology of manifolds and disk embedding), 무은재 석좌교수 기념강연 (Mueunjae Chair Professor Lecture), May 22, 2017, POSTECH, Pohang, Korea.
12. Whitney towers in a rational homology ball, Invariants in Low-dimensional Topology, May 12, 2017, KIAS, Seoul, Korea.
13. Milnor invariants and rational Whitney towers, April 19, 2017, Indiana University, Bloomington, Indiana, USA.
14. $L^2$-acyclic bordism and Whitney towers, The 12th East Asian School of Knots and Related Topics, February 14, 2017, University of Tokyo, Japan.
15. Disk embedding in dimension four, The 2nd KAST and Lincei bilateral symposium, December 6, 2016, Seoul, Korea.
16. Mathematics of dimension 4, KAIST CMC Noon Lecture, December 2, 2016, KAIST, Daejeon, Korea.
17. A quantitative approach to Cheeger-Gromov rho invariants and 4-dimensional bordism, October 25, 2016, Hausdorff Research Institute for Mathematics, Bonn, Germany.
18. 4-dimensional $L^2$-acyclic bordism and Whitney towers, Conference on 4-manifolds and knot concordance, October 17, 2016, Max Planck Institute for Mathematics, Bonn, Germany.
19. 4-manifold topology and disk embedding, Math Colloquium, October 6, 2016, Seoul National University, Seoul, Korea.
20. $L^2$-acyclic bordism groups of 3-manifolds, Topology in Dimension 3.5: a conference in memory of Tim Cochran, June 4, 2016, Rice University, Houston, Texas, USA.
21. Complexity and Gromov norm of 3-manifolds, International workshop of PMI, May 19, 2016, POSTECH, Pohang, Korea.
22. Quantitative topology and Cheeger-Gromov universal bounds, April 27, 2016, Seoul National University, Seoul, Korea.
23. Disk embedding in dimension 4, Math Colloquium, March 17, 2016, KAIST, Daejeon, Korea.
24. A survey on topological concordance and disk embedding, BIRS workshop: Synchronizing Smooth and Topological 4-Manifolds, February 22, 2016, Banff, Canada.
25. A topological approach to Cheeger-Gromov universal bounds of von Neumann rho invariants, Geometry/Topology Seminar, February 18, 2016, University of Chicago, USA.
26. Casson towers, gropes, and disk embedding, The 11th East Asian School of Knots and Related Topics, January 29, 2016, Osaka City University, Japan.
27. Controlled chain homotopy and von Neumann rho-invariants of Cheeger and Gromov, East Asian Conference on Algebraic Topology, December 3, 2015, NIMS, Daejeon, Korea.
28. Complexities of 3-manifolds, Knots and Spatial Graphs 2015, November 6, 2015, KAIST, Daejeon, Korea.
29. Topology of dimension 4 and disk embedding, Math Colloquium, May 22, 2015, Ajou University, Suwon, Korea.
30. Von Neumann-Cheeger-Gromov rho invariants and topology of 3-manifolds, The 10th East Asian School of Knots and Related Topics, January 28, 2015, East China Normal University, Shanghai, China.
31. Topological manifolds of dimension 4 and disk embedding, Math Colloquium, November 27, 2014, Konkuk University, Seoul, Korea
32. Cheeger-Gromov universal bounds of von Neumann L2 rho-invariants,  Algebraic Structures in Low-Dimensional Topology, May 26, 2014, Mathematisches Forschungsinstitut Oberwolfach, Germany.
33. A new approach to Cheeger-Gromov universal bounds of L2 rho invariants, March 18, 2014, Brandeis University, Waltham, Massachusetts, USA.
34. A topological approach to Cheeger-Gromov universal bounds, March 5, 2014, Indiana University, Bloomington, Indiana, USA.
35. Universal bounds for the Cheeger-Gromov rho-invariants, February 28, 2014, University of Wisconsin, Madison, Wisconsin, USA.
36. A topological viewpoint to Cheeger-Gromov rho invariants, GAIA-Institute Fourier Joint Conference on Geometry, July 15, 2013, Pohang, Korea.
37. Universal bounds of Cheeger-Gromov invariants: a topological viewpoint, February 4, 2013, Rice University, Houston, Texas, USA.
38. Covering link calculus and the bipolar filtration of links, The 9th East Asian School of Knots and Related Topics, January 15, 2013, University of Tokyo, Tokyo, Japan.
39. Homology cobordism of 3-manifolds and lower central series, December 4, 2012, Syracuse University, Syracuse, New York, USA.
40. The bipolar filtration of topologically slice links, AMS Fall Central Sectional Meeting, Special Session on Knot Theory and 4-manifolds, October 20, 2012, University of Akron, Akron, Ohio, USA.
41. Amenable L2-signatures and cobordism of knots and 3-manifolds, October 11, 2012, Harvard University, Cambridge, Massachusetts, USA.
42. Homology cobordism and lower central series of 3-manifold groups, October 10, 2012, Brandeis University, Waltham, Massachusetts, USA.
43. Amenable L2-signatures and homology cobordism of 3-manifolds, September 12, 2012, Indiana University, Bloomington, Indiana, USA.
44. Cobordism of knots and 3-manifolds, International Conference of Honam Mathematical Society, June 15, 2012, Jeju National University, Jeju, Korea.
45. Some recent results on links, 3-manifolds, Whitney towers and amenable Cheeger-Gromov invariants, Tokyo workshop on low dimensional topology, March 20, 2012, Tokyo Institute of Technology, Tokyo, Japan.
46. Hidden torsion in 3-manifold groups and homology cobordism, The 8th East Asian School of Knots and Related Topics, January 11, 2012, Daejeon, Korea.
47. An introduction to $L^2$-invariants I, II, III, The 8th East Asian School of Knots and Related Topics, January 9-11, 2012, Daejeon, Korea.
48. Invariants of cobordism of knots and 3-manifolds, Invited talk at 2011 Fall Meeting of Mathematical Society of Japan, September 28, 2011, Shinshu University, Matsumoto City, Nagano, Japan.
49. Whitney towers, knot concordance, and amenable L2-theoretic methods, International Conference in Memory of Hyo Chul Myung, April 27, 2011, Seoul, Korea.
50. Homology localization of groups, injectivity theorems, and amenable L2-homological methods, The 1st Euro-Korean Conference on Groups and Related Topics, March 30, 2011, Pohang, Korea.
51. Knots in dimension 3 and topology of dimension 4, Math Colloquium, KAIST, March 24, 2011, Daejeon, Korea.
52. Applications of covering link calculus, Topology Seminar, Indiana University, February 09, 2011, Bloomington, Indiana, USA.
53. Signatures of manifolds and knots, 2011 Winter Workshop for Young Mathematicians in Korea, January 28, 2011, Pohang, Korea.
54. Whitney towers and Amenable L2-techniques, The 7th East Asian School of Knots and Related Topics, Hiroshima University, January 13, 2011, Hiroshima, Japan.
55. Amenable L2-theoretic methods for knots and 3-manifolds, Topology Seminar, Seoul National University, October 21, 2010, Seoul, Korea.
56. L2-signatures: twisted invariants from duality, RIMS Seminar, Twisted topological invariants and topology of low-dimensional manifolds, September 17, 2010, Akita, Japan.
57. Why is the twisted Alexander polynomial related to fiberability? RIMS Seminar, Twisted topological invariants and topology of low-dimensional manifolds, September 15, 2010, Akita, Japan.
58. L2-signatures and homology cobordism of 3-manifolds, Lecture series on L2-invariants of knots and manifolds, August 11-13, 2010, KIAS, Seoul, Korea.
59. Homological L2-invariants of knots and manifolds I, II, III, Lecture series on L2-invariants of knots and manifolds, August 11-13, 2010, KIAS, Seoul, Korea.
60. Amenable L2-theoretic methods and applications to knots and 3-manifolds, The 2nd TAPU-KOOK Joint Seminar, July 30, 2010, Kyungpook National University, Daegu, Korea.
61. Introduction to L2-invariants, Knot Concordance and Homology Cobordism Workshop, July 23, 2010, Wesleyan University, Middletown, Connecticut, USA.
62. Amenable L2-theoretic methods and applications, Knot Concordance and Homology Cobordism Workshop, July 22, 2010, Wesleyan University, Middletown, Connecticut, USA.
63. Homology and L2-signatures from amenable groups, The 6th East Asian School of Knots and Related Topics, January 27, 2010, Chern Institute of Mathematics, Tianjin, China.
64. L2-signature defects and amenable groups, Special Session on Knot Theory and Related Topics, Joint Meeting of the Korean Mathematical Society and the American Mathematical Society, December 18, 2009, Seoul, Korea.
65. L2-signatures, homology, and amenable groups, International Conference on Symplectic, Contact and Low Dimensional Topology, November 12, 2009, Seoul, Korea.
66. Links in dimension 3 and their deformation in dimension 4, Chonbuk National University, September 24, 2009, Jeonju, Korea.
67. Torsion in link concordance and Hirzebruch-type invariants from iterated p-covers, Canadian Mathematical Society Summer Meeting, June 7, 2009, St. John’s, Newfoundland, Canada.
68. Links and intersection form defects, Mathematical Colloquium, Seoul National University, May 14, 2009, Seoul, Korea.
69. The structure of the rational concordance group of knots, Excellent Research Paper Award Lecture, 2009 Spring Meeting of the Korean Mathematical Society, April 25, 2009, Suwon, Korea.
70. Links in 3-space and their deformation in 4-space, Mathematical Colloquium, Yonsei University, April 9, 2009, Seoul, Korea.
71. Local derived series, L2-signatures, and applications to manifolds, The 5th East Asian School of Knots and Related Topics, January 13, 2009, Gyeongju, Korea.
72. Using Artin reciprocity in knot theory, Kyushu-POSTECH joint workshop on number theory and related topics, January 6, 2009, Pohang, Korea.
73. Deformation of links in dimension 4, Mathematical Colloquium, Chungang University, November 21, 2008, Seoul, Korea.
74. 4-dimensional deformation of links in the 3-space, Mathematical Colloquium, Sogang University, October 9, 2008, Seoul, Korea.
75. Slicing and non-slicing iterated Bing doubles, Topology-Geometry Seminar, Indiana University, August 26, 2008, Bloomington, Indiana, USA.
76. Link concordance, homology cobordism, and iterated p-covers, Fifty years since Fox and Milnor: a conference on knot concordance in honor of the memory of Jerry Levine, Brandeis University, June 3, 2008, Waltham, Massachusetts, USA.
77. Link concordance and Hirzebruch-type invariants from iterated covers, Pusan Nation University, April 18, 2008, Pusan, Korea.
78. Slicing iterated Bing doubles, a plenary talk at The 4th East Asian School of Knots and Related Topics, January 21, 2008, Tokyo, Japan.
79. Non-slice iterated Bing doubles, Topology Seminar, UC Berkeley, November 14, 2007, Berkeley, California, USA.
80. Homology, injectivity theorems, and algebraic closures with coefficients, East Asian Conference of Algebraic Topology, November 3, 2007, Seoul, Korea.
81. New Hirzebruch-type invariants from iterated p-covers, The 7th KAIST Geometric Topology Fair, July 9, 2007, Gyeongju, Korea.
82. An elementary tutorial on provable security, KIAS-KMS Summer workshop on Cryptography, June 29, 2007, Seoul, Korea.
83. Invariants of homology cobordism and link concordance from towers of itrated abelian p-covers, Geometric Topology Conference, Peking University, June 19, 2007, Beijing, China.
84. The structure of the rational knot concordance group, Department of Mathematics, POSTECH, May 23, 2007, Pohang, Korea.
85. Introduction to Geometric Topology and Knot Theory, Departmental Colloquium, Department of Mathematics, Konkuk University, April 13, 2007, Seoul, Korea.
86. Hirzebruch-Atiyah-Singer type invariants of manifolds and applications to knot theory, Department of Mathematics, Ewha Womans University, March 30, 2007, Seoul, Korea.
87. Witt class defect invariants, homology cobordism, and link concordance, a talk at The Third East Asian School of Knots and Related Topics in Geometric Topology, February 6, 2007, Osaka, Japan.
88. Classifications of manifold embeddings, Mathematical Colloquium, Korea Institute for Advanced Study, November 22, Seoul, Korea.
89. Invariants from Atiyah-type theorems and applications to links, an invited talk at 2006 Geometry & Topology Day at Konkuk University, November 18, 2006, Seoul, Korea.
90. Homology equivalences, injectivity theorems, and algebraic closures of groups, an invited talk at NIMS Workshop on Geometry and Topology, November 16, 2006, Daejeon, Korea.
91. The structure of the concordance group of knots in rational homology spheres, an invited talk at 2005 fall meeting of the Korean Mathematical Society, 21 October, 2005, Seoul, Korea.
92. Algebraic closures with coefficients and torsion-free derived series, a plenary talk at The Second East Asian School of Knots and Related Topics in Geometric Topology, August 4, 2005, Dalian, China.
93. Algebraic closures with coefficients and applications to homology cobordism, January 31, 2005, Department of Mathematics, Rice University, Houston, Texas, U.S.A.
94. Homology equivalences and algebraic closures, January 24, 2005, Department of Mathematics, Indiana University, Bloomington, Indiana, U.S.A.
95. Classification of knots from the viewpoint of manifold theory, November 25, 2004, Department of Mathematics, Konkuk University, Seoul, Korea.
96. Classification of knots from the viewpoint of manifold theory, November 4, 2004, Department of Mathematics, Ewha Womans University, Seoul, Korea.
97. Torsion-free derived series, algebraic closures, and link concordance, The First KAIST Geometric Topology Fair, August 25, 2004, Chungju, Korea.
98. Randomized computation and provable security I, II, Korea Institute for Advanced Study, August 6-7, 2004, Seoul, Korea.
99. Rational homology concordance of knots, BIRS Workshop on Knots and Their Manifold Stories, May 11, 2004, Banff, Alberta, Canada.
100. Provable security of ID-based cryptosystems, National Security Research Institute, March 11, 2004, Daejeon, Korea.
101. Concordance of knots in rational homology spheres, The First East Asian School of Knots, Links, and Related Topics, February 17, 2004, Seoul, Korea.
102. Localization, surgery and placement problems of manifolds, Departmental Colloquium, Department of Mathematics, Korea Advanced Institute of Science and Technology, December 4, 2003, Daejeon, Korea.
103. Concordance and rational knots, Korea Advanced Institute of Science and Technology, March 27-28, 2003, Daejeon, Korea.
104. The structure of the rational knot concordance group, AMS special session, March 14, 2003, Baton Rouge, Louisiana, U.S.A.
105. The effect of mutation on link concordance, 3-manifolds, and the Milnor invariants, AMS special session, January 17, 2003, Baltimore, Maryland, U.S.A.
106. Concordance and rational knots, Knots in Washington XV, January 10, 2003, Washington, DC, U.S.A.
107. Computation of rational knot concordance, October 8, 2002, Brandeis University, Waltham, Massachusetts, U.S.A.
108. A survey on link concordance, January 15, 2002, Nara Women’s University, Nara, Japan.
109. Implementations of braid cryptosystems, An invited tutorial in International Workshop on Practice and Theory in Public Key Cryptography, February 13, 2001, Cheju, Korea
110. Link concordance theory in rational homology spheres and its application to concordance of homology boundary links, KNOTS 2000, August 2, 2000, YoungPyong, Kangwon, Korea.