The demand for LNG Carrier and LNG fuel ships are increasing due to global carbon neutrality declaration and ship emissions regulation of IMO, domestic shipyards pay technology fees(about 5~10% of ship price per vessel) to GTT company in France for making LNG cargo hold. Localization of LNG cargo hold is needed to reduce technology fees and engage technological competitiveness, it is important to secure the critical technology like automation process development of insulation system process. Especially, the automation rate of membrane-type insulation system is very low due to interference caused by corrugation and difficulty in securing optimal variable welding condition. In this study, to solve this problem, automatic welding is performed using developed automatic welding equipment on STS304L steel which is used in flat and corner area of membrane-type LNG cargo hold's lap joint. After welding, Cross-sectional observations and Tensile strength tests were conducted to evaluate reliability of equipment and welding condition. As a result of the test, it was confirmed that the strength of the welded zone exceeded that of base material, and secured the optimal welding condition to apply automatic welding.

The research model of panel data analysis in this study was used as the dependent variables and the business characteristics of the welding industry were reflected in the research model for systematic analysis of the effect of welding technology on the welding industry. As a result of the existing research, the domestic welding technology is seriously encroaching on the domestic welding industry between the United States, Japan and China. There is no quantitative statistical analysis on this aspect. In this study, the panel data analysis is used to indicate differences in explanatory power by numerical values of POLS model, fixed effect and random effect. And the prior studies on the current status of welding industry related to arc welding, special welding, multiple welding, welding and bonding technology are applied by the panel data analysis. Therefore, the problems of existing research are diagnosed while presenting the future research directions.

To precisely assemble the fuel test rod, an orbital TIG welding system was designed and developed to accurately conduct orbital TIG welding for the nuclear fuel test rod. Using this system, a welding process needs to confirm the welding properties for orbital TIG welding. Therefore, preliminary weld tests were performed on the cladding tubes under various conditions, and the results show that the width and depth of HAZ of the cladding specimen welded using identical power during an orbital TIG welding cycle was continuously increased from a welded start-point to a welded end-point because of heat accumulation. The performance tests were conducted under the welding conditions considered through preliminary welding tests, and the properties of the specimens were conformed through surface and microstructure analyses.

The shock absorber base assembly is one of the parts in the shock absorber equipment that controls the vehicle movement. It absorbs the shock and vibration to guarantee riding stability and comfort. It demands strength, reliability and strict airtightness

Shock absorber base assembly is one of the parts in shock absorber equipment which control the vehicle movement and absorb the shock and vibration to realize the stability and the comfort for the riding. This part demand hardness, reliance and rigorous density of the welded section because it is a resist pressure container which needs durability by being filled with gas and oil. However, the present engineering needs much time, high cost and shows low production rate due to the eight processes which are spot welding, reinforcement welding(MAG), prior process of base cap and tube for the precision and pressing etc. In this study we will analyze the problem of the processes for the base assembly and suggest an engineering to improve the problem innovatively using frictional welding. As the result of experiment by frictional welding using frictional heat, its hardness for the joining section became high and its precision showed excellence. Therefore we can expect the curtailment for the welding processes, the reduction of cost and excellent joining function.

본 논문은 선박용 알루미늄 합금에 대하여 TIG, MIG 그리고 로봇을 이용한 용접 등과 같은 다양한 용접기술을 적용하여 기계적 특성을 평가하였다. TIG 용접을 실시하였을 경우는 항복강도, 인장강도 그리고 연신율은 모재에 비하여 각각 83.9%, 64.6% 그리고 21.9%를 나타냈다. MIG 용접은 ER5356 용접봉을 사용하여 용접한 경우 ER5183 용접봉을 사용한 경우에 비하여 기계적 특성이 대략 2-4% 정도 개선된 효과가 관찰되었다. 또한 로봇을 이용한 용접을 실시한 경우는 5456-H116 모재에 비하여 5083O 모재의 경우가 양호한 기계적 특성을 나타냈다.