Cosmic-ray protons (CRp) are ubiquitous in astrophysical environments. They are known to be accelerated via various processes, involving shock waves, turbulence, magnetic reconnection, and etc. These CRp can produce high-energy neutrinos through inelastic collisions with background protons and photons. In this talk, we present possible astrophysical sources of high-energy neutrinos in the energy range of 1 to 100 GeV, and discuss the possibility of detecting such neutrinos with the KNO (Korean Neutrino Observatory).