Research.

Digraphs in which every t vertices have exactly λ common out-neighbors

with Myungho Choi, Suh-Ryung Kim

Structural properties of symmetric Toeplitz and Hankel matrices

with Homoon Ryu

A digraph version of the Friendship Theorem

with Myungho Choi, Suh-Ryung Kim

Competition graphs of degree bounded digraphs

with Suh-Ryung Kim

For this research, I received a grant (with the same title) from Basic Science Research Program, National Research Foundation of Korea (KRW 20,000,000).

On strong odd colorings of sparse graphs

with Ilkyoo Choi

Connectivity keeping paths in digraphs

with Boram Park, Homoon Ryu

A sharp extension of Halin's removable-edge theorem to matchings

Minimum degree conditions for removable matchings in k-connected graphs

with Ringi Kim, Boram Park

On 2-connected graphs without cycles of length 1 modulo 3

with Yandong Bai, Binlong Li, Boram Park, Homoon Ryu

Existence of cycles of length divisible by 3 or 4

with Ilkyoo Choi, Ringi Kim, Boram Park

Connectivity keeping trees in triangle-free graphs

with Shinya Fujita, Boram Park, Homoon Ryu

On 2-connected graphs avoiding cycles of length 0 modulo 4

with Boram Park, Homoon Ryu

Linear-time computation of the Frobenius normal form for symmetric Toeplitz matrices via graph-theoretic decomposition

with Homoon Ryu

Competition-common enemy graphs of degree-bounded digraphs

with Myungho Choi, Suh-Ryung Kim

Digraphs in which every t vertices share exactly λ out-neighbors and exactly λ in-neighbors

with Suh-Ryung Kim

Planarity of generalized ladder graphs

with Suh-Ryung Kim, Homoon Ryu