Abstract: Provided is a positive electrode active material capable of achieving a lithium secondary battery having excellent initial charge and discharge efficiency, life characteristics, and thermal stability and a preparation method thereof, wherein the positive electrode active material of the present invention includes a core portion including a lithium transition metal oxide wherein a mole ratio of nickel (Ni) in total transition metals is 80 mol % or more, and a layer-structured shell portion formed on the core portion and including a lithium transition metal oxide in which a molar ratio of manganese (Mn) in the total transition metals is 30 mol % or more, and satisfies Equation 1: 0.005 ? Thickness ? of ? the ? shell ? portion ( ?m ) Average ? particle ? diameter ( D 50 ) ? of ? the ? positive ? electrode ? ? active ? material ( ?m ) ? 0.15 .

Abstract: Provided is an optical system which may acquire a hyperspectral image by acquiring a spectral image of an object to be measured, which includes, to collect spectral data and train the neural network, an image forming part forming an image from an object to be measured and transmitting collimated light, a slit moving to scan the incident image and passing and outputting a part of the formed image, and a first optical part obtaining spectral data by splitting light of the image received through the slit by wavelength. Also, the system includes, to decompose overlapped spectral data and to infer hyperspectral image data through the trained neural network, an image forming part forming an image from an object to be measured and transmitting collimated light, and a first optical part obtaining spectral data by splitting light of the received image by wavelength.

Abstract: A semiconductor rectifier includes a substrate of a first conductivity type; a current path layer of the first conductivity type formed near the surface of the substrate; a current block layer of a second conductivity type laterally enclosing the current path layer and extending to a depth deeper than the current path layer; and first and second metal layers formed respectively contacting upper and lower surfaces of the substrate. The current path layer has an impurity concentration higher than that of the substrate, and the current block layer has an impurity concentration higher than that of the current path layer. The current path layer is small enough for the portion below the current path layer to be completely blocked by the depletion region formed around the current block layer when a reverse bias or no is applied to the rectifier.