I would like to give my intellectual journey that led to the involvements in gravitational wave science.

My PhD thesis was about the dynamical evolution of dense star clusters including the effects of the binaries and stellar collisions.

The black holes are interesting objects in view of the stellar dynamics in many aspects.

The observational evidence for the supermassive black hole was growing rapidly in late 1980s as the high resolution spectroscopic observations became available,

and the advancement of the speckle interferometry toward the Galactic Center.

My research area expanded to the origin of the supermassive black holes and their interactions with surrounding stars.
In  2000, I was invited to a LISA symposium held in Golm, Germany, where I was first exposed to the gravitational wave experiments.

I felt that the gravitational wave would become an important tool for astronomy and formed a gravitational-wave study group in late 2003.

From 2004, the Korean Gravitational Wave Group (KGWG) organized summer schools every year under the sponsorship

of Asian-Pacific Center for Theoretical Physics (APCTP) and Korea Institute for Science and Technology Information (KISTI) focusing on the general relativity

and gravitational waves and educated ourselves on these topics.

In 2009, KGWG became a member of the LIGO Scientific Collaboration.

While working on the LIGO collaboration, I also continued to study the roles of the black holes in star clusters and found that the black hole merger events

could be more abundant than neutron star binary coalescence in LIGO observations.

The gravitational wave community in Korea is growing and KASI now pursues gravitational wave experiments by developing the measurement techniques
that could enhance the sensitivity significantly.

I will close my talk by giving prospects of gravitational wave astrophysics.