Abstract: Disclosed is an endoscope apparatus. The endoscope apparatus of the present invention includes: an endoscope including a flexible insertion section to be inserted into a human body; a flexible channel attached to the insertion section so that a part forms a passage in a longitudinal direction of the insertion section; and an assistant arm movably inserted into the passage and manipulated by a control device, and the assistant arm includes forceps capable of gripping a human body tissue, and a bending section bent by the control device to pull the human body tissue griped by the forceps.

Abstract: An atomic layer etching method using a ligand exchange reaction may include a substrate providing step of putting a substrate with a thin film formed thereon into a reaction chamber, a halogenated thin film forming step of forming a halogenated thin film on a surface of the thin film by infusing a halogenated gas into the reaction chamber, and an etching step of etching the halogenated thin film by infusing a ligand without a metal or metal precursor into the reaction chamber with the substrate with the halogenated thin film.

Abstract: A paper feeding device to sense various sizes of paper according to a sensing voltage output from a sensor and an image forming apparatus having the same includes a body to receive paper in which an image is printed thereon. The image forming apparatus further includes a paper feeding device to feed paper into the body. The paper feeding device includes a paper tray in which paper is loaded, and paper guides that are slidably installed to the paper tray to guide left and right ends of paper loaded in the paper tray in a paper feeding direction. A light reflector is installed to be moved in linkage with the paper guides and includes a stepped reflection surface. A sensor emits light to the light reflector and receives the light reflected by the light reflector to determine the sizes of paper.