This study improved the work efficiency by supplementing the shortcomings of the manual process by developing a double tube feeding device, and the following results were obtained by conducting the production capacity, production length, and defect rate tests. Developed a double tube production system to enable the simultaneous production of two tubes, increasing the production volume by about 1.5 times. The product length has been improved from semi-automatic to automated, and the production capacity has been improved from 16 to 25 pieces per hour (based on 15m). Developed a double-tube input straight line automatic adjustment feeder, which resulted in reducing the defect rate to less than 1%.

Due to its excellent processability, thermal conductivity and high corrosion resistance, copper tubes applied to heat exchangers are being joined through brazing to increase heat exchange efficiency. In order to improve performance, the issue of joint quality of copper tubes, a major member of heat exchangers, is emerging, so research is needed to obtain excellent joint quality of brazing joints that may be damaged. In this study, the quality change of joints according to process variables was studied through induction heating brazing experiments using high frequency. The depth of penetration, which indicates the quality of the junction, was measured, and the center position of the high-frequency electrode and the height of the electrode, which change the location of the heat source applied to the junction, were selected as process variables. Lastly, the thermal image data obtained between the brazing experiments were obtained and the joint quality according to the temperature gradient of the joint was analyzed.

The use of heat exchangers in various applications such as chemical, air conditioning systems, fuel processing, and power industries is increasing. In order to improve the performance of the heat exchanger, the problem of bonding quality of the copper tube, which is a major member, is emerging. However, since the copper tube is in the form of a pipe, it is difficult to identify internal defects with external factors. In this study, a thermal imaging camera was used to develop and verify an algorithm for detecting defects in the brazing part, and in the process, the brazing performance characteristics were analyzed according to the electrode position, and finally, a learning model was developed and performance evaluation was performed. It was confirmed that the method of supplying heat to the base material and melting the filler metal through the heat transfer effect is more effective than supplying heat input to the filler metal in the bonding process of copper tubes through high-frequency induction heating brazing. Thermal image data was used to develop a defect discrimination model, and 80% of training data and 20% of test data were selected, and a neural network-based single-layer copper tube brazing defect discrimination model was developed through k-Flod cross-validation., the prediction accuracy of 95.2% was confirmed as a result of the error matrix analysis.

A powder-in-sheath rolling (PSR) process utilizing a copper alloy tube was applied to a fabrication of a multi-walled carbon nanotube (CNT) reinforced aluminum matrix composite. A copper tube with an outer diameter of 30 mm and a wall thickness of 2 mm was used as a sheath material. A mixture of pure aluminum powders and CNTs with the volume contents of 1, 3, 5 vol% was filled in the tube by tap filling and then processed to 93.3% height reduction by a rolling mill. The relative density of the CNT/Al composite fabricated by the PSR decreased slightly with increasing of CNTs content, but showed high value more than 98%. The average hardness of the 5%CNT/Al composite increased more than 3 times, compared to that of unreinforced pure Al powder compaction. The hardness of the CNT/Al composites was some higher than that of the composites fabricated by PSR using SUS304 tube. Therefore, it is concluded that the type of tube affects largely on the mechanical properties of the CNT/Al composites in the PSR process.