Abstract: Provided is a heat treatment method of an alloy for eco-friendly vehicle parts, the heat treatment method including preparing an aluminum (Al) alloy, performing solid solution treatment on the Al alloy, performing primary cooling to a temperature range of 250° C. to 400° C. after the solid solution treatment is performed, and performing secondary cooling to room temperature after the primary cooling is performed, wherein a cooling rate range of the primary cooling is lower than the cooling rate range of the secondary cooling.

Abstract: Disclosed are a soft recoil system and a cannon having the same. The soft recoil system includes: a cannon barrel returning device mounted to a recoil device for absorbing a recoil force occurring when ammunition is fired, and configured to backward press a breech ring, such that the cannon barrel is fixed to a preset position; a cannon barrel fixing device installed at the recoil device, and configured to fix the cannon barrel when the cannon barrel returns to the fixed position; and a forward momentum generator connected to the recoil device and the breech ring, respectively, configured to forward move the cannon barrel by applying a force to the breech ring, such that the ammunition is fired while the cannon barrel forward moves, and configured to reduce a recoil force by partially attenuating recoil momentum resulting from the firing of the ammunition, by forward momentum.

Abstract: Disclosed are a soft recoil system and a cannon having the same. The soft recoil system includes: a cannon barrel returning device mounted to a recoil device for absorbing a recoil force occurring when ammunition is fired, and configured to backward press a breech ring, such that the cannon barrel is fixed to a preset position; a cannon barrel fixing device installed at the recoil device, and configured to fix the cannon barrel when the cannon barrel returns to the fixed position; and a forward momentum generator connected to the recoil device and the breech ring, respectively, configured to forward move the cannon barrel by applying a force to the breech ring, such that the ammunition is fired while the cannon barrel forward moves, and configured to reduce a recoil force by partially attenuating recoil momentum resulting from the firing of the ammunition, by forward momentum.

Abstract: Disclosed herein is an optical access network system in which the transmission quality of an upstream signal is remarkably improved in an optical access network in which a Reflective Semiconductor Optical Amplifier (RSOA) is used as the light source for each subscriber. The most important characteristics of the present invention are that a Manchester modulation format is used as a modulation format for a downstream signal in an optical access network system in which an RSOA is used as the light source for each subscriber, so that the problem of deterioration of the transmission quality of a remodulated upstream signal, occurring when an RSOA is used as the light source for each subscriber, is solved, and thus the transmission performance of an upstream signal and the power budget performance of the entire system are improved.