### 2014

- November 27, 2014: Colloquium, Department of Mathematics, Duksung Women’s University, Seoul.
- From the Four Color Theorem to Hadwiger’s Conjecture

- November 14, 2014: Colloquium, Department of Mathematics, Korea University, Seoul.
- Ramsey-type theorem for graphs without splits

- July 21, 2014: 2014 International Workshop on Structure in Graphs and Matroids, Princeton University, Princeton, NJ, USA.
- Constructive algorithm for path-width and branch-width of matroids

- July 5, 2014: 수학골든벨 KAIST 프로그램, KAIST, Daejeon.
- Road to become a mathematician (수학자의 길에 관한 이야기)

- July 5, 2014: Institute of Science Education for the Gifted (과학영재교육원), Choongnam National University, Daejeon.
- Infinite numbers (무한)

- June 27, 2014: KMRS Seminar, Department of Mathematical Sciences, KAIST, Daejeon.
- An algorithm for path-width and branch-width of matroids

- June 16, 2014: Minisymposium “Graph Structure – Part I of II”, SIAM Conference on Discrete Mathematics, Minneapolis, MN, USA.
- Unavoidable vertex-minors in large prime graphs

- April 18, 2014: Colloquium, Department of Mathematics, POSTECH, Pohang.
- Ramsey-type theorem for graphs without splits

- March 13, 2014: Colloquium, Department of Mathematics, Sogang University, Seoul.
- Ramsey-type theorem for graphs without splits

- March 8, 2014: 3rd KIAS Combinatorics Workshop, KIAS, Seoul.
- Unifying duality theorems for width parameters

- January 28, 2014: Working Group Seminar, University of Hamburg, Hamburg, Germany (with Reinhard Diestel).
- Unifying duality theorems for width parameters in finite graphs

- January 14, 2014: Working Group Seminar, University of Hamburg, Hamburg, Germany.
- Hyperbolic surface subgroups of one-ended doubles of free groups

### 2013

- December 16, 2013: Monday Lecture, Institut für Mathematik, Technische Universität Berlin, Berlin, Germany.
- Vertex-minors and split decompositions of graphs

- November 14, 2013: Institutskolloquium, Institut für Informatik, University of Rostock, Rostock, Germany.
- Vertex-minors of graphs

- October 1, 2013: DIMAP Seminar, Center for Discrete Mathematics and its Applications, University of Warwick, UK.
- Vertex-minors of graphs

- July 1, 2013: Special Session on Combinatorics and Graph Theory, the Asian Mathematical Conference AMC2013 (June 30-July 4), Busan, Korea.
- Excluded vertex-minors for graphs of linear rank-width at most k

- June 24, 2013: Special Session on Combinatorics and Discrete Mathematics, 2nd Pacific Rim Mathematical Association Congress (June 24-28), Shanghai, China.
- June 5, 2013: Working Group Seminar, University of Hamburg, Hamburg, Germany (with O-joung Kwon).
- Unavoidable vertex-minors for large prime graphs

- April 19, 2013: Research Seminar, University of Hamburg, Hamburg, Germany.
- Width-parameters and tree-decompositions of graphs and matroids

- April 14, 2013: Vortrag im Seminar Diskrete Mathematik und Optimierung, Institut für Optimierung und Diskrete Mathematik, Technische Universität Graz, Graz, Austria.
- Even cycle decompositions of graphs with no odd K
_{4}minor

- Even cycle decompositions of graphs with no odd K
- March 20, 2013: Dagstuhl workshop “Bidimensional Structures: Algorithms, Combinatorics and Logic” (March 17-22), Schloss Dagstuhl, Dagstuhl, Germany.
- Forbidden vertex-minors for graphs of linear rank-width at most k

- February 21, 2013: Working Group Seminar, University of Hamburg, Hamburg, Germany
- Vertex-minors and pivot-minors, concepts and overview

- January 30, 2013: グラフ・ネットワークにおける理論と最適化グループセミナー (Graph Network Theory and Optimization Group Seminar), National Institute of Informatics, Tokyo, Japan.
- Well-quasi-ordering conjecture for pivot-minors

- January 22, 2013: KAIST 글로벌 사이언스 리더 캠프 (2012학년도 부산광역시 과학영재교육원 겨울집중수업), KAIST 영재교육센터.
- 짝지우기, 그래프 이론, 수학

### 2012

- December 7, 2012: KAIST 일반전형 창의인성면접자 합격생 워크샵 및 멘토링 프로그램, KAIST.
- KAIST 선배의 경험담

- November 15, 2012: 자연과학강좌, Chungbuk National University, Cheongju.
- 4색 정리 이야기 (Story on Four Color Theorem)

- October 27, 2012: 2012 International Conference on Graph Theory, Combinatorics and Applications (October 27-30), Zhejiang Normal University, Jinhua, China.
- Even cycle decomposition of graphs with no odd K
_{4}minor

- Even cycle decomposition of graphs with no odd K
- October 18, 2012: Discrete Convexity and Optimization (October 15-18), RIMS Workshop, Kyoto, Japan.
- Even cycle decomposition of graphs with no odd K
_{4}minor

- Even cycle decomposition of graphs with no odd K
- October 5, 2012: Invited talk, 2012 KMS Fall Meeting (October 5-6), Daejeon.
- Even cycle decomposition of graphs with no odd K
_{4}minor

- Even cycle decomposition of graphs with no odd K
- August 20, 2012: Invited session on structural graph theory and methods, 21st International Symposium on Mathematical Programming (August 19-24), Berlin, Germany.
- July 24, 2012: 젊은 지성과의 만남, 영스타클럽(Korean Science and Technology Young Stars Club) 포럼 (July 24-25, 2012), KAIST
- August 3, 2012: Third workshop on graphs and matroids (July 29-August 4), Maastricht, The Netherlands
- Even cycle decomposition of graphs with no odd K
_{4}minor

- Even cycle decomposition of graphs with no odd K
- June 19, 2012: SIAM Conference on Discrete Mathematics(June 18-21), Dalhousie University, Halifax, Nova Scotia, Canada.
- Rank-Width and Well-Quasi-Ordering of Skew-Symmetric Or Symmetric Matrices

- June 1-7, 2012: Mini-school on Widths-Minors-Matroids, Department of Informatics, University of Bergen, Bergen, Norway.
- June 1: Relation of rank-width with clique-width
- June 4: Rank-width and vertex-minors; their relations to binary matroid minors
- June 5: Branch-width of symmetric submodular functions and their recognition algorithms
- June 6: Excluded pivot-minors for rank-width
- June 7: Isotropic systems and vertex-minors; how to write C2MS logic formula for testing vertex-minors

- May 9, 2012: Graph Theory @ Georgia Tech, Conference Honoring the 50th Birthday of Robin Thomas (May 7-11), Georgia Tech, Atlanta, USA.
- Graphs of small rank-width is a pivot-minor of graphs of small tree-width

- April 12, 2012: Colloquium, Department of Mathematics, Chonbuk National University, Jeonju, Korea.
- Survey on vertex-minors and pivot-minors

### 2011

- December 14, 2011: The Second Bertinoro Workshop on Algorithms and Graphs, Bertinoro, Italy.
- Rank-width and well-quasi-ordering of skew-symmetric or symmetric matrices

- November 8, 2011: Robin Thomas Fest, Charles University, Prague, Czech.
- Rank-width and well-quasi-ordering of skew-symmetric or symmetric matrices

- October 18, 2011: Seminar, Department of Computer Science and Engineering, Seoul National University, Seoul.
- Vertex-minors, Monadic Second-Order Logic, and a Conjecture by Seese

- September 2, 2011: European Conference on Combinatorics, Graph Theory, and Applications (Eurocomb), Budapest, Hungary.
- Rank-width and well-quasi-ordering of skew-symmetric or symmetric matrices

- August 18, 2011: Combinatorics Workshop (2011 조합론 학술대회), Kangwon National University, Chuncheon.
- Computing Rank-width Exactly

- August 4, 2011: 2011 초등 수학과학 영재교사 직무연수, 충남대학교 과학영재교육원, Choongnam National University, Daejeon.
- 4색 정리 이야기 (Story on Four Color Theorem)

- June 28, 2011: Noon Lecture, Department of Applied Mathematics (KAM), Charles University, Prague.
- Vertex-minors and pivot-minors of graphs

- June 10, 2011: Special Department Seminar, Department of Mathematics, Yeungnam University, Kyoungsan.
- A survey on vertex-minors and pivot-minors

- April 29, 2011: Special Session on Graph Theory, Korean Mathematical Society Spring Meeting, Korea University, Seoul.
- Rank-width and Well-quasi-ordering of Skew-symmetric or Symmetric Matrices

- April 19, 2011: 자연과학대학 대중강연 (Public Lecture of College of Natural Science), KAIST.
- 4색정리 이야기 (Story on Four Color Theorem)

- April 11, 2011: 유학준비생을 위한 강연, KAIST.
- February 16, 2011: Graph Algorithm and Combinatorial Optimization, NII Shonan Meeting, Shonan Village Center, Japan.
- Rank-width and Well-quasi-ordering of Skew-symmetric or Symmetric Matrices

### 2010

- December 3, 2010: Public Lecture, 금요일에 과학터치, 대전교육과학연구원, Daejeon.
- Mathematics of Matchings (짝지우기의 수학)

- November 17, 2010: Kyoto Prize Satellite Workshop in Tokyo in honor of Professor László Lovász, Tokyo Institute of Technology, Tokyo.
- Hyperbolic surface subgroups of doubles of free groups

- September 9, 2010: New trends on structural graph theory, Banff Workshop, Banff, Canada.
- Hyperbolic surface subgroups of doubles of free groups

- August 25, 2010: 대구과학고 아카데미 강연, Daegu Science High School, Daegu.
- August 23, 2010: Robot Vision 연구회 세미나, Samsung 생산기술연구소, Suwon.
- 그래프이론 소개 (Introduction to Graph Theory)

- August 20, 2010: Invited Talk, 2010 Combinatorics Workshop, Yeungnam University, Gyeongsan
- Hyperbolic surface subgroups of one-ended doubles of free groups

- August 13, 2010: Invited Lecture, KAIST 수학문제연구회 영재캠프, KAIST, Daejeon
- Mathematics of Matchings (짝지우기의 수학)

- June 21, 2010: 40th Algebraic Combinatorics Seminar, Kyungpook National University, Daegu.
- Well-quasi-ordering conjecture for pivot-minors

- June 16, 2010: Minisymposium on Structural Graph Theory, SIAM Conference on Discrete Mathematics, Austin, Texas, USA.
- Perfect matchings in claw-free cubic graphs

- April 24, 2010: Lecture for KMS Excellent Paper Award, KMS Spring Meeting, Korean Mathematical Society, Choongnam National University, Daejeon.
- Vertex-minors, monadic second-order logic, and a conjecture by Seese

- April 24, 2010, Invited Public Lecture, Korean Women in Mathematical Society (한국여성수리과학회), Choongnam National University, Daejeon.
- Mathematics of Matchings (짝지우기의 수학)

- April 17, 2010: The 3rd Annual Meeting of the Asian Association for Algorithms and Computation (AAAC2010), POSTECH, Pohang.
- Computing rank-width exactly

- March 24, 2010: Invited Seminar, National Institute of Mathematical Sciences (NIMS), Daejeon.
- Rank-width of Random Graphs

- February 15-19, 2010: One-Week Workshop on New Development of Discrete Algorithms, Tokyo Institute of Technology, Tokyo, Japan.
- (2/15) Testing branch-width at most k for fixed k or non-fixed k

- February 10, 2010: The First Wednesday Multidisciplinary Forum (첫수융합포럼), KAIST.
- Matchings

- January 11-13, 2010: Winter School on Algorithms and Combinatorics, Jochiwon, Korea.
- (1/12) Parameterized Complexity
- (1/13) Width Parameters of Graphs

### 2009

- December 19, 2009: Special session on combinatorial matrix theory, Joint Meeting of the Korean Mathematical Society and the American Mathematical Society, Ewha Womans University, Seoul.
- Perfect matchings in claw-free cubic graphs

- December 17, 2009: Parameterized complexity and approximation algorithms, Dagstuhl, Germany.
- Algorithms on Rank-width

- December 10, 2009: Bertinoro Workshop on Graphs and Algorithms, Bertinoro, Italy.
- Perfect matchings in claw-free cubic graphs

- October 20, 2009: Informatics Colloquium, Faculty of Informatics, Masaryk University, Brno, Czech Republic.
- Maximum number of complete subgraphs in a certain graph

- October 16, 2009: Fourth workshop on Graph Classes, Optimization, and Width Parameters (GROW 2009), Bergen, Norway.
- Computing rank-width exactly

- September 17, 2009: Colloquium, Department of Mathematics, Sungkyunkwan University, Suwon, South Korea.
- Vertex-minors and pivot-minors of graphs

- June 8, 2009: 첨단과학세미나, Korea Science Academy (한국과학영재학교), Pusan, South Korea.
- Planar graphs and circle graphs

- June 4, 2009: 2009 ASARC Workshop, Muju resort, South Korea.
- A survey on vertex-minors and pivot-minors

- May 9, 2009: DIMACS Workshop on Graph Colouring and Structure, Princeton University, Princeton, New Jersey, USA.
- April 25, 2009: 2009 KMS Spring Meeting, Department of Mathematis, Ajou University, Suwon, South Korea.
- Maximum number of complete subgraphs in a certain graph

- February 4, 2009: KAIST Combinatorics Seminar, Department of Mathematical Sciences, KAIST, Daejeon, South Korea.
- Maximum number of complete subgraphs in a certain graph

- January 30, 2009: 2009 ASARC Workshop at Daecheon, Daecheon, South Korea.
- Maximum number of complete subgraphs in a certain graph

- January 9, 2009: Seminar, Department of informatics, University of Bergen, Bergen, Norway.
- Maximum number of complete subgraphs in a certain graph

- January 8, 2009: Department Seminar, Department of informatics, University of Bergen, Bergen, Norway.
- Introduction to Rank-width

### 2008

- December 22, 2008: Kyoto RIMS Winter School on Graphs and Algorithms, RIMS, Kyoto University, Kyoto, Japan.
- Survey on Rank-width and Clique-width

- November 5, 2008: Math Club, Department of Mathematics, POSTECH
- Seese’s conjecture on the decidability of the monadic second-order theory

- November 1, 2008: 수학문제연구회 20주년 기념행사 (20th year anniversary event of KAIST Mathematical Problem Solving Group), KAIST Mathematical Problem Solving Group, KAIST.
- 그래프 집합 위에서의 단항이차논리식의 결정가능성에 관한 Seese의 추론

- October 16, 2008: Colloquium, Department of Mathematics, Ajou University, Suwon, Korea.
- Seese’s conjecture on the decidability of the monadic second-order theory

- September 30, 2008: Graph minors, Banff International Research Station, Banff, Canada.
- Tree-width and rank-width of H-minor-free graphs

- August 7, 2008: 2008 Combinatorics Workshop, Sungkyungkwan University, Suwon, Korea.
- Finding branch-decompositions and rank-decompositions.

- July 20, 2008: The Netherlands Workshop on Graphs and Matroids, Sittard, the Netherlands.
- Graphic delta-matroids

- June 24, 2008: Fudan-KAIST Joint Workshop on Applied Mathematics, School of Mathematical Sciences, Fudan University, Shanghai, China.
- Chain theorems for 4-prime graphs

- June 16, 2008: SIAM Conference on Discrete Mathematics, University of Vermont, Burlington, Vermont, USA.
- Chain theorems for 4-prime graphs

- June 12, 2008: Kyoto RIMS Workshop on Combinatorial Optimization and Discrete Algorithms, Research Institute for Mathematical Sciences (RIMS), Kyoto University, Kyoto, Japan.
- Apr. 7, 2008: Workshop on Graph Decomposition: Theoretical, Algorithmic and Logical Aspects, CIRM, Luminy, France.
- Apr. 3, 2008: Combinatorics Seminar, LaBRI, Bordeaux, France.
- Line graphs of large rank-width

- Mar. 28, 2008: Special session on Structural graph theory, AMS sectional meeting, Baton Rouge, Lousiana, USA.
- Chain theorems for 4-prime graphs

- Feb. 21, 2008: Undergraduate Colloquium (학부생 콜로퀴엄), Department of Mathematical Sciences, KAIST.
- Four Color Theorem

- Feb. 1, 2008: 4th Korea-Japan Workshop on Algebra and Combinatorics, POSTECH, Pohang, Korea.
- Well-quasi-ordering of skew-symmetric matrices of bounded rank-width

### 2007

- Dec. 3, 2007: Colloquium, Department of Computational and Applied Mathematics, Rice University, Houston, Texas, USA.
- Introduction to Rank-wdth

- Nov. 27, 2007: Combinatorial Optimization Seminar, University of Waterloo, Waterloo, Ontario, Canada.
- Finding Branch-decompositions and Rank-decompositions

- Nov. 16, 2007: Joint Combinatorics – Theory Seminar, University of Toronto, Toronto, Canada.
- Introduction to Rank-width

- Oct. 19, 2007: The Third Workshop on Graph Classes, Optimization, and Width Parameters, Eugene, Oregon, USA.
- Aug. 6-8, 2007: 2007 Combinatorics Workshop, KAIST, Daejeon, Korea.
- Circle graphs obstructions under pivoting (Aug. 6)
- Excluding a bipartitie circle graph from line graphs (Aug. 7)
- Rank-width and well-quasi-ordering (Aug. 8 )

- Jul. 25, 2007: Structure Theory and FPT Algorithms for Graphs, Digraphs and Hypergraphs, Dagstuhl workshop 07281, Germany.
- May 28, 2007: 1st Canadian Discrete and Algorithmic Mathematics Conference (CanaDAM 2007), Banff, Alberta, Canada.
- Circle graph obstructions under pivoting

- May 10, 2007: Colloquium, Department of Mathematics, Yonsei University, Seoul, Korea.
- Survey on rank-width and clique-width

- May 8, 2007: Special Lecture, Department of Mathematics, POSTECH, Pohang, Korea.
- Survey on rank-width and clique-width

- May 2, 2007: Colloquium, Department of Mathematical Sciences, KAIST, Daejeon, Korea.
- Survey on rank-width and clique-width

- Mar. 28, 2007: Oberwolfach Workshop
*Graph Theory*, Oberwolfach, Germany.- Excluded pivot-minor characterization of circle graphs

- Jan. 23, 2007: Combinatorial Optimization Seminar, University of Waterloo, Canada.
- Circle graph obstructions under pivoting

### 2006

- Nov. 16, 2006: Graph Theory Seminar, Georgia Institute of Technology, USA.
- Circle graph obstructions under pivoting

- Aug. 4, 2006: Tutte Seminar, University of Waterloo, Canada.
- Survey on rank-width and clique-width

- Jul. 21, 2006: Horizon of Combinatorics, Lake Balaton, Hungary.
- Excluding a bipartite circle graph from line graphs

- Jul. 11, 2006: Sixth Czech-Slovak International Symposium on Combinatorics, Graph Theory, Algorithms and Applications, Prague, Czech Republic.
- Excluding a bipartite circle graph from line graphs

- Jun. 25, 2006: SIAM Conference on Discrete Mathematics, Victoria, British Columbia, Canada.
- Towards a Grid Theorem for Rank-width and Clique-width

- May 20, 2006: The XXVIIIth Ohio State-Denison Mathematics Conference, Columbus, OH, USA.
- Towards a Grid Theorem for Rank-width and Clique-width

- Apr. 27, 2006: Graph Theory Seminar, Georgia Institute of Technology, USA.
- Towards a Grid Theorem for Rank-width and Clique-width

- Feb. 9, 2006: Graph Theory Seminar, Georgia Institute of Technology, USA.
- Testing Branch-width

- Jan. 23, 2006: ACM/SIAM Conference on Discrete Algorithms (SODA), Miami, FL, USA.

### 2005

- Dec. 27, 2005: Combinatorics Seminar, Department of Mathematics, KAIST, Daejeon, Korea.
- Nov. 24, 2005: Combinatorics and Optimization Seminar, University of Waterloo, Waterloo, Canada.
- Testing Branch-width

- Oct. 18, 2005: Workshop on Graph Classes, Width Parameters and Optimization, Prague, Czech.
- Oct. 13, 2005: Graph Theory Seminar, Georgia Institute of Technology, USA.
- Graphs of Bounded Rank-width II

- Oct. 12, 2005: Combinatorics Seminar, Georgia Institute of Technology, USA.
- Rank-width and Well-quasi-ordering of Skew-symmetric Matrices

- Oct. 6, 2005: Graph Theory Seminar, Georgia Institute of Technology, USA.
- Graphs of Bounded Rank-width

- Sep. 24, 2005: The 41st Midwest Graph Theory Conference, Middle Tennessee State University, Murfreesboro, TN, USA.
- Approximating Rank-width and Clique-width Quickly

- Sep. 13, 2005: 7th International Colloquium on Graph Theory (ICGT ’05), Hyères, France.
- Rank-width and well-quasi-ordering of skew-symmetric matrices

- Jul. 26, 2005: Exact Algorithms and Fixed-Parameter Tractability, Dagstuhl workshop, Germany.
- Jul. 3, 2005: Princeton-Oxford Workshop, Oxford, UK.
- Jun. 23, 2005: 31st International Workshop on Graph-Theoretic Concepts in Computer Science, Metz, France.
- Jun. 20, 2005: Seminar on graphs and logic, University of Bordeaux 1, Bordeaux, France.
- Graphs of Bounded Rank-width

- Jun. 16, 2005: Séminaire de Combinatoire Algébrique et Géométrique, Combinatoire et Optimisation, Université Pierre et Marie Curie (Paris 6), Paris, France
- Jan. 19, 2005: Oberwolfach Workshop “
*Graph Theory*“, Oberwolfach, Germany

### 2004

- Dec. 17, 2004: Workshop “
*Graph and Hypergraph Decompositions – Methods and Applications in Computer Science*“, Vienna, Austria - Nov. 19, 2004: PACM Graduate Student Seminar, Princeton University
- Rank-width and Well-quasi-ordering

- Nov. 15, 2004: Discrete Mathematics and Optimization Seminar, McGill University, Montreal, Quebec, Canada
- Oct. 29, 2004: Graph Theory Seminar, Georgia Institute of Technology
- Oct. 1-2, 2004: two talks were given at the Satellite Workshop
*Logic, Graph Transformations, Finite and Infinite Structures*of the 2nd International Conference on Graph Transformations (IGCT) in Rome, Italy. Titles are - May. 23, 2004:
*Robust and Approximative Algorithms on Particular Graph Classes*, a Dagstuhl seminar - Mar. 10, 2004:
*Princeton Discrete Mathematics Seminar*- From binary matroids to graphs

- Feb. 27, 2004:
*PACM Graduate Student Seminar*- From binary matroids to graphs

### 2003

- Dec. 13, 2003:
*Advances in Graph and Matroid Theory*, A conference in honour of Neil Robertson’s 65^{th}birthday - Jun. 25-28, 2003:
*Oxford/Princeton Workshop*- Approximating Clique-width

- Mar. 28, 2003:
*PACM Graduate Student Seminar*- Polynomial-time Approximation Algorithm for the Clique-Width of graphs