Research interests Combinatorics, qseries and special functions
Publications  (with SenPeng Eu and Seunghyun Seo) Enumerations of vertices among all rooted ordered trees with levels and degrees, arXiv:1605.00715, to appear in Discrete Mathematics, 2017.
 (with Jiang Zeng) Symmetric unimodal expansions of excedances in colored permutations, arXiv:1411.6184, European Journal of Combinatorics, 52, part A, 174196, 2016. / MR3425973
 (with Seunghyun Seo) Signed apolynomials of graphs and Poincaré polynomials of real toric manifolds, arXiv:1212.6307, Bulletin Korean Mathematical Society, 52(2), 467481, 2015. / MR3338206
 (with Jang Soo Kim and Seunghyun Seo) Annular noncrossing permutations and minimal transitive factorizations, arXiv:1201.5703, Journal of Combinatorial Theory, Series A, 124, 251262, 2014. / MR3176201
 (with Seunghyun Seo) A refinement for pary labeled trees, arXiv:1311.7492, Korean Journal of Mathematics, 21(4), 495502, 2013.
 (with Seunghyun Seo) A refinement for ordered labeled trees, arXiv:1207.3291, Korean Journal of Mathematics, 20(2), 225261, 2012.
 (with Jiang Zeng) The symmetric and unimodal expansion of Eulerian polynomials via continued fractions, arXiv:1005.4583, European Journal of Combinatorics, 33(2), 111127, 2012. / MR2854634
 (with Seunghyun Seo) On the enumeration of rooted trees with fixed size of maximal decreasing trees, arXiv:1106.1290, Discrete Mathematics, 312(2), 419426, 2012. / MR2852601
 (with Sohyun Hwang et al) Contextdependent transcriptional regulations between signal transduction pathways, BMC Bioinformatics 2011, 12:19, 2011.
 (with Yoann Gelineau and Jiang Zeng) Bijections for Entringer families, arXiv:1004.2179, European Journal of Combinatorics, 32(1), 100115, 2011. / MR2727465
 (with Jiang Zeng) A bijective enumeration of labeled trees with given indegree sequence, arXiv:0805.0067, Journal of Combinatorial Theory, Series A, 118(1), 115128, 2011. / MR2737188
 (with Jiang Zeng) The qtangent and qsecant numbers via continued fractions, arXiv:0911.4658, European Journal of Combinatorics, 31(7), 16891705, 2010. / MR2673011
 (with Jiang Zeng) An involution for symmetry of hook length and part length of partitions, arXiv:0907.4880, Discrete Mathematics, 310(1011), 16331639, 2010. / MR2601273
 (with Seunghyun Seo) A generalized enumeration of labeled trees and reverse prüfer algorithm, arXiv:math/0601009, Journal of Combinatorial Theory, Series A, 114(7), 13571361, 2007. / MR2353128
 (with Manwon Cho et al) Colored prüfer codes for kedge colored trees, Electronic Journal of Combinatorics 11(1), N10, 2004. / MR2097341
Conference Proceedings (with Jang Soo Kim and Seunghyun Seo) Minimal transitive factorizations of a permutation of type (p,q), FPSAC 2012, 2012. / PDF
 (with Jiang Zeng) A further correspondence between (bc,b)parking functions and (bc,b)forests, FPSAC 2009, 2009. / DMTCS Proceedings AK, 793804.
 (with Seunghyun Seo) Two involutions on vertices of ordered trees, FPSAC 2002, 2002. / PDF
Preprints (with Suyoung Choi) On a decomposition of simple polytopes, in preparation, 2010.
 A refined bijection between alternating permutations and 012 increasing trees, arXiv:1003.4564, preprint, 2010.
 A new bijection between forests and parking functions, arXiv:0810.0427, submitted, 2008.
Talks Hot to use JupyterHub for mathematics, Math Colloquium, Inha University, Incheon, Korea, March 29, 2017.
 Welcome to Python and SageMath, SageMath Developers Meeting 2017, Sungkyunkwan University, Korea, Feb. 1, 2017
 Hot to use JupyterHub for data analysis, Setup of JupyterHub and its application, Korea University, Korea, Dec. 9, 2016.
 Enumerations of vertices among all rooted ordered trees with levels and degrees, The 12th KIAS Combinatorics Workshop, KIAS, Seoul, Korea, June 3, 2016. / silde
 Education and research by SageMath, Mathematical Software Working Seminar, Korea University, Seoul, Korea, June 12, 2015.
 Continued fractions and generalized Fibonacci numbers, 2014 Combinatorics Workshop, Ajou University, Suwon, Korea, October 31, 2014.
 Eulerian polynomials via continued fractions: Part 2, The 2nd KIAS Combinatorics Workshop, KIAS, Seoul, Korea, December 20, 2013.
 Eulerian polynomials via continued fractions, The 1st KIAS Combinatorics Workshop, KIAS, Seoul, Korea, November 8, 2013.
 Simsun permuations and Entringer families, Enumerative Combinatorics mini Workshop 2013, Ladena Condominium, Chuncheon, March 30, 2013.
 (Poster) Minimal transitive factorizations of a permutation of type (p,q), FPSAC 2012, Nagoya, Japan, 2012.
 Trees and parking functions, Math Colloquium, Inha University, Incheon, Korea, March 9, 2011.
 Bijections for Entringer families, 9th JapanKorea Workshop on Algebra and Combinatorics, Tohoku University, Sendai, Japan, January 25, 2011.
 On qenumeration of permutations, KAIST Discrete Math Seminar, KAIST, Daejeon, Korea, November 19, 2010.
 Certain expansion of Eulerian polynomials via continued fractions, 41st Algebraic Combinatorics Seminar, POSTECH, Pohang, Korea, November 6, 2010.
 On a generalization of Eulerian polynomials via continued fractions, 2010 Global KMS International Conference, POSTECH, Pohang, Korea, October 22, 2010.
 Symmetry and supersymmetry distribution for partitions, SLC 63, Centro Residenziale Universitario di Bertinoro, Bertinoro, Italy, September 2730, 2009. / slide
 Symmetry and supersymmetry distribution for partitions, 2009 Combinatorics Workshop, KAIST, Daejeon, Korea, August 2021, 2009.
 (Poster) A further correspondence between (bc,b)parking functions and (bc,b)forests, FPSAC 2009, Hagenberg, Austria, July 2024, 2009.
 Counting labelled trees with given indegree sequence, Journées du GDR Informatique Mathématique, Lyon, France, June 1516, 2009.
 Forests and parking functions, SLC 61, Grande Hotel da Curia, Curia, Portugal, September 2124, 2008. / slide
 Counting labelled trees with given indegree sequence, KAIST Discrete Math Seminar, KAIST, Daejeon, Korea, August 21, 2008.
 On a decomposition of simple polytopes, Séminaire de Théorie des Nombres et Combinatoire, ICJ, Lyon, France, November 27, 2007.
 On a decomposition of simple polytopes, 2007 Combinatorics Workshop, KAIST, Daejeon, Korea, August 68, 2007.
 The bijection between forests and parking functions, 2006 Combinatorics Workshop, Yeoungnam University, Gyeongsan, Korea, August 10, 2006.
 The similarity of forests and parking functions, 2006 Lectures, Center for Combinatorics, Nankai University, Tianjin, China, August 2, 2006.
 Forests and parking functions, 13th Algebraic Combinatorics Seminar, Pusan National University, Pusan, Korea, June 10, 2006.
 Combinatorial objects for qexponential functions, 2005 Combinatorial Mathematics Conference, Yonsei University, Seoul, Korea, August 810, 2005.
 Permutation patterns, ordered trees and continued fractions, 2002 KMS Spring Conference, Hoseo University, Cheonan, Korea, April 27, 2002.

