Research Area

• Enumerative Combinatorics
• Algebraic Combinatorics

Visiting Position

• 2004-2005, Visiting Scholar, Department of Mathematics, Brandeis University (mentor: Ira Gessel)
• 2016-2017, Visiting Scholar, Department of Mathematics, The Pennsylvania State University (mentor: Ae Ja Yee)

Publications

1. Singular overpartitions and partitions with prescribed hook differences (with Ae Ja Yee), Annals of Combinatorics 23(2019), 1039-1072.
2. Refined enumeration of vertices among all rooted ordered d-trees (with Sangwook Kim and Heesung Shin), Bulletin of Korean Mathematical Society 56(4) (2019), 899-910.
3. Enumeration of partitions with prescribed successive rank parity blocks (with Ae Ja Yee), Journal of Combinatorial Theory, series A 158(2018), 12-35.
4. Overpartitions and singular overpartitions (with Ae Ja Yee), In: Andrews G., Garvan F. (eds) Analytic Number Theory, Modular Forms and q-Hypergeometric Series. ALLADI60 2016. Springer Proceedings in Mathematics & Statistics, vol 221. Springer, Cham, (2017), 693-711.
5. Enumerations of vertices among all rooted ordered trees with levels and degrees (with Sen-Peng Eu and Heesung Shin), Discrete Mathematics 340(9) (2017), 2123-2129.
6. Colored permutations with no monochromatic cycles (with Dongsu Kim and Jang Soo Kim), Journal of Korean Mathematical Society 54(4) (2017), 1149-1161.
7. The Catalan threshold arrangement, Journal of Integer Sequences 20(1) (2017), Article 17.1.1.
8. Combinatorial enumeration of the regions of some linear arrangements, Bulletin of Korean Mathematical Society 53(5) (2016), 1281-1289.
9. Signed a-polynomials of graphs and Poincaré polynomials of real toric manifolds (with Heesung Shin), Bulletin of Korean Mathematical Society 52(2) (2015), 467-481.
10. Annular noncrossing permutations and minimal transitive factorizations (with Jang Soo Kim and Heesung Shin), Journal of Combinatorial Theory, series A 124(2014), 251-262.
11. Shi-threshold arrangements, Electronic Journal of Combinatorics 19(3) (2012), P39.
12. Enumeration of 0/1-matrices avoiding some 2x2 matrices (with Hyeong-Kwan Ju), Discrete Mathematics 312(16) (2012), 2473-2481.
13. A refinement for ordered labeled trees (with Heesung Shin), Korean Journal of Mathematics 20(2) (2012), 255-261.
14. On the enumeration of rooted trees with fixed size of maximal decreasing trees (with Heesung Shin), Discrete Mathematics 312(2) (2012), 419-426.
15. Combinatorial proofs of inverse relations and log-concavity for Bessel numbers (with Hyuk Han), European Journal of Combinatorics 29(2008), 1544-1554.
16. A Generalized enumeration of labeled trees and reverse Prüfer algorithm (with Heesung Shin), Journal of Combinatorial Theory, series A 114 (2007), 1357-1361.
17. An efficient top-down search algorithm for learning Boolean networks of gene expression (with Dougu Nam, Sangsoo Kim), Machine Learning 65(1) (2006), 229-245.
18. A refinement of Cayley's formula for trees (with Ira Gessel), Electronic Journal of Combinatorics 11(2) (2006), R27.
19. A combinatorial proof of Postnikov's identity and a generalized enumeration of labeled trees, Electronic Journal of Combinatorics 11(2) (2005), N3.
20. Colored Prüfer codes for k-edge colored trees (with Manwon Cho et al), Electronic Journal of Combinatorics 11(1) (2004), N10.
21. Transitive cycle factorizations and prime parking functions (with Dongsu Kim), Journal of Combinatorial Theory, series A 104 (2003), 125-135.