The Milky Way’s Ancient Starburst: A Glimpse into Its Violent Past

Recent observations suggest that the Milky Way (MW) underwent a major collision with the Gaia-Sausage/Enceladus (GSE) dwarf galaxy approximately 8 to 10 billion years ago. While GSE has since been completely disrupted, its merger brought in ex situ stars that formed outside the MW, while in situ stars from the MW’s primordial disk were displaced […]

Galactic Archaeology with Large Survey Data

Galactic Archaeology is a field that uses fossils of stars and dwarf galaxies around the Milky Way (MW) to reconstruct the formation and evolution history of the MW. This talk introduces how to use large spectroscopic data from the Sloan Digital Sky Survey and Large Sky Area Multi-Object Fiber Spectroscopic Telescope and astrometric data from […]

The critical mass in galaxy evolution

Observations of low-redshift galaxies reveal a mass threshold where many properties and scaling relations undergo significant transitions. This "critical mass," at a stellar mass of logM* ~10.5, signifies the shift from star-forming, disc-dominated galaxies to passive, spheroid-dominated systems. Key scaling relations of galaxies, such as the size-mass, mass-metallicity, and stellar mass-halo mass relations, show changes […]

Abrupt sea level rise and Earth’s gradual pole shift reveal permanent hydrological regime changes in the 21st century

Rising atmospheric and ocean temperatures have caused substantial changes in terrestrial water circulation and land surface water fluxes, such as precipitation and evapotranspiration, potentially leading to abrupt shifts in terrestrial water storage. The European Centre for Medium-Range Weather Forecasts (ECMWF) Reanalysis v5 (ERA5) soil moisture (SM) product reveals a sharp depletion during the early 21st century. During the […]

SKA 프로젝트와 한국의 참여

SKA(Square Kilometre Array) 프로젝트는 전 세계가 협력하여 건설 중인, 인류 역사상 가장 거대한 전파 망원경입니다. 호주와 남아프리카 공화국에 건설되는 SKA는 50MHz에서 15GHz에 이르는 광범위한 주파수 대역을 관측하며, 기존 전파 망원경을 압도하는 감도와 속도로 하늘을 탐사합니다. SKA는 두 단계로 건설되는데, 2030년 과학 관측 착수 예정인 SKA1은 전체 망원경의 약 10% 규모입니다. SKA는 연 700페타바이트의 방대한 관측 […]

인공위성으로 바라본 지구와 기후변화

인공위성을 활용한 지구환경 원격탐사는 50년 이상의 역사와 함께하고 있다. 그 중 기상위성은 지구에서 방출되는 빛 에너지를 관측하여, 이를 2차원 혹은 3차원으로 시각화하여, 대기 중 수증기, 구름, 그리고 미세먼지 등의 모니터링에 활용되고 있다. 기상변수 뿐 아니라 해수면온도, 토양수분량, 극지 해빙 변수 등 대기, 해양, 지질을 아우르는 변수의 산출도 기술력의 향상과 함께 가능해졌다. 본 세미나에서는 인공위성으로 바라본 […]

The first all-sky infrared spectro-photometric survey mission, SPHEREx

The SPHEREx (Spectro-Photometer for the History of the Universe, Epoch of Reionization, and Ices Explorer) is a NASA MIDEX astrophysics mission designed to provide the first all-sky infrared spectro-photometric data. This ambitious mission aims to probe the origins of the Universe, explore the formation and evolution of galaxies, and investigate the potential for planets around […]

Optical Communications in Space, 우주 광통신

The telecommunication has been an essential and indispensable service for humans. Deep space communication is challenging for us to extend our scope into the outer space such as the Moon and Mars. Radio communications have provided us with a lot of convenience so far, but it is confronted with the limits of bandwidths and data […]

Principles of Generative AI and How to Use, Optimize, and Improve It

We are witnessing an unprecedented surge in AI advancements. While AI has been a subject of hype for years, recent breakthroughs—driven by generative AI (e.g., ChatGPT)—have made it more powerful and widely applicable than ever. In this talk, I will explore the fundamental principles behind the two foundational techniques of generative AI: large language models […]