<My collaborators>

Stephen Childress (PhD advisor; New York Univ. Courant Institute, USA)

Hisashi Okamoto (Long time mentor and coworker; Gakushuin Univ. Japan)

June-Yub Lee (Long time colleague, Ewha Woman Univ.)

Sung-Ik Sohn (Long time colleague, Gnagneung-Wonju Univ.)

Larry Chen(deceased, RIP), Ronald B. Guenther, Enrique A. Thomann , Edward Waymire (Oregon State Univ. USA)

Seungsu Hwang (Long time colleague, Chung-Ang Univ.)

Tomoyuki Miyaji (Meiji Univ. Japan)

Takashi Sakajo (Kyoto Univ. Japan)

In-Jee Jeong (Seoul National Univ.)

Seung-Yeal Ha, Dohyun Kim, Chanho Min (Seoul National Univ.)

Jongbin Yoon, Habin Im (Students, Chung-Ang Univ.)

(*Chronological order)