Name 
Talk 
Kim Jin Young 
Perturbation of a natural AdS wormhole in EinsteinBornInfeld gravity
We consider the scalar perturbations of a new AdS wormhole in (3+1)dimensional EinsteinBornInfeld gravity. We discuss the stability of the perturbation by numerically computing the quasinormal modes of a massive scalar field in the wormhole background. We investigate the dependence of quasinormal frequencies on the mass of the scalar field as well as other parameters of the wormhole. It is found that the perturbations are always stable for the wormhole geometry which has the general relativity limit when the scalar mass has a certain tachyonic mass bound analogous to the BreitenlohnerFreedman (BF) bound in the globalAdS space.

Kim SungWon 
Creation and Evolution of Cosmological Horizons in FLRW Universe with Wormhole
Recently we solved the Einstein's field equations to obtain the exact solution of the cosmological model with the MorrisThorne type wormhole. We found the apparent horizons and analyzed their geometric natures, including the causal structures. We also derived the Hawking temperature near the apparent cosmological horizon. In this paper, we investigate the dynamic properties of the apparent horizons under the matterdominated universe and lambdadominated universe. As a more realistic universe, we also adopt the $\Lambda$CDM universe which contains both the matter and lambda. The past light cone and the particle horizon is examined for what happens in the case of the model with wormhole. Since the spatial coordinates of the spacetime with the wormhole are limited outside the throat, the past light cone can be operated by removing the smallerthanwormhole region. The past light cones without wormhole begin start earlier than the past light cones with wormhole in conformal timeproper distance coordinates. The light cone consists of two parts: the information from our universe and the information from other universe or far distant region through the wormhole. Therefore, the particle horizon distance determined from the observer's past light cone cannot be defined in a unique way.

Lee ChangHwan 
Tidal deformability of neutron stars and gravitational waves
Gravitational waves (GW170817) produced in a binary neutron star inspiral have been observed followed by gammaray burst (GRB 170817A) and afterglows from Xray to radio. By combining the distance obtained by gravitational waves and red shift obtained by electromagnetic waves, even Hubble constant has been estimated. This indicates the start of new era of multimessenger astronomy. In addition to the masses of inspiralling neutron stars, the tidal deformability which depends on the inner structure of neutron stars has been estimated from gravitational waves. This confirms that even strong interactions can be tested by gravitational waves. In this talk, I review the effect of tidal deformability of neutron stars to the gravitational waves produced in the inspiral process, and discuss the implications of detected tidal deformability to the neutron star equations of state.

Lee Hyung Won 
Equation of motion for test particle in modified gravity
We calculated the equation of motion for the modified gravity theory introduced by us recently. We will study in detail for this modified gravity to see the possibility of explaining galaxy rotational curve and dark matter content.

Yeom Donghan 
Quantum gravitational aspects inside a black hole
We investigate inside a black hole using quantum gravitational methods. We solve the WheelerDeWitt equation for the interior of the Schwarzschild black hole. As a result, we can obtain interesting interpretations, where this can give the wisdom to understand the information loss paradox of black holes.
