Due to stricter environmental regulations of the International Maritime Organization(IMO), the number of ships fueled by Liquefied Natural Gas(LNG) is rapidly increasing. The International Code of the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk(IGC Code) limits the material of tanks that can store cryogenic substances such as LNG. Among the materials listed in the IGC Code, ASTM A553M-17 has been recently adopted as a material for LNG fuel tank projects because of its excellent mechanical properties at cryogenic temperatures. In shipyards, this material is being used to build tanks through Flux Cored Arc Welding (FCAW). However, there is a problem that magnetization occurs during welding and there is a big difference in welding quality depending on the welding position. In order to overcome this problem, this study intends to conduct basic research to apply laser welding to ASTM A553M-17 material. In this study, a study on penetration (HAZ depth, Penetration) and welding defects during fiber laser welding according to three types of shielding gases(nitrogen, argon, and helium) was conducted. To this end, a Bead on plate(BOP) experiment was performed under four fiber laser conditions(Power, Speed) for each shielding gas and welding defects caused by the use of the shielding gas were compared through cross-sectional observation, and the penetration depth was analyzed.

The electrochemical carbon dioxide reduction to produce acetaldehyde, methanol and ethanol is investigated by using perovskite type electrode (La0.9Sr0.1CuO3). The experiments were performed under 100 mA/㎠ and -2 to -2.5 V vs. Ag/AgCl. The highest faradaic efficiencies for methanol, ethanol, acetaldehyde were 11.6, 15.3, and 6.2%, respectively. The experimental data demonstrated that the capability of the perovskite type oxide for the electrode of electrochemical carbon dioxide reduction to produce alcohols was superior to other metal electrode.