Abstract: An image display system includes a body, a first correction unit, and a second correction unit. The body houses a display unit to display an image and projects a virtual image, corresponding to the image, onto a target space using outgoing light of the display unit. The first correction unit corrects for distortion of the image. The second correction unit corrects a display location of the image on the display unit in accordance with an orientation signal representing a change in orientation of the body. Each of divisional areas of a display screen of the display unit is assigned with a distortion correction parameter for correcting for the distortion of the virtual image. The first correction unit applies distortion correction to each of the image regions of the image on the display screen based on a distortion correction parameter assigned to a divisional area where the image region is displayed.

Abstract: In a first process of a method of gas carburizing, a steel treatment object in a carburizing atmosphere containing carburizing gas is heated to an initial set temperature which is not higher than a peritectic point at which ? iron and a liquid phase transform into ? iron and not less than a eutectic point at which the liquid phase transforms into ? iron and cementite, such that the surface carbon concentration thereof does not exceed a solid solubility limit. In a second process following the first process, the carburizing temperature is gradually decreased from the initial set temperature such that the surface carbon concentration of the treatment object increases without exceeding the solid solubility limit, and such that the carburized depth of the treatment object increases.

Abstract: In a first process of a method of gas carburizing, a steel treatment object in a carburizing atmosphere containing carburizing gas is heated to an initial set temperature which is not higher than a peritectic point at which ? iron and a liquid phase transform into ? iron and not less than a eutectic point at which the liquid phase transforms into ? iron and cementite, such that the surface carbon concentration thereof does not exceed a solid solubility limit. In a second process following the first process, the carburizing temperature is gradually decreased from the initial set temperature such that the surface carbon concentration of the treatment object increases without exceeding the solid solubility limit, and such that the carburized depth of the treatment object increases.