The paint removal of fighter jets is just as important as the painting, because perfect paint removal ensures the quality of the exterior painting on the aircraft. However, the current conditions for paint removal work of the ROKAF’s are poor. It is identified that the painting process currently implemented by the ROKAF is not only exposed to harmful compounds such as harmful dust and hexavalent chromium, but also consumes a lot of water. Thus, the introduction of advanced facility is considered. This study compares the fighter jets painting removal process currently applied by the Korean Air Force with the improved laser coating removal process of the US Air Force, and conducts an incremental analysis to perform economic analysis for the introduction of advanced facility. Four scenarios were envisioned on the premise of an increase in the number of fighters in the future, incremental analysis shows that laser coating removal method is advantageous in all scenarios. In addition, it is recommended that paint removal cycle keeps the current 12-year and the outsourcing amount to civilian depot is reduced.

The Korean Air-Force aircraft maintenance depot paints the exterior of various aircraft, including high-tech fighters. Aircraft exterior painting is a maintenance process for long-term life management by preventing damage to the aircraft surface due to corrosion. The de-painting process is essential to ensure the quality of aircraft exterior paints. However, because the Korean Air-Force’s de-painting process is currently done with sanding or Plastic Media Blasting (PMB) method, it is exposed to harmful dust and harmful compounds and consumes a lot of manpower. This study compares the de-painting process currently applied by the ROK Air-Force and the more improved process of the US Air Force, and performs economic analysis for the introduction of advanced equipment. It aims to provide information that can determine the optimal time to introduce new facilities through Cost-Volume-Profit (CVP) analysis. As a result of the analysis, it was confirmed that the sanding method had the most economical efficiency up to 2 units per year, the PMB method from 3 to 21 units, and the laser method from 22 units or more. In addition, in a situation where the amount of de-painting work is expected to increase significantly due to the increase in fighters in future, BEP analysis was conducted on the expansion of the existing PMB method and the introduction of a new laser method. As a result of the analysis, it was confirmed that it is more economical to introduce the laser method when the amount of work exceeds the PMB work capacity(18 units per year). The paper would helpful to improve the productivity and quality of the Korean Air Force Aircraft maintenance depot through timely changes of facilities in the workplace in preparation for expansion.

본 논문은 Shaped charge jet(SCJ)의 관통 과정을 유한요소해석을 통해 모사하여 제트 입사속도, 관통률 그리고 관통량 증분과 같은 물리량들을 획득하였다. 이 물리량들을 hydrodynamic 이론에 적용하여 입사 제트 속도의 효율을 분석한 결과, 입사 속도가 빠른 제트의 관통 효율은 이어지는 느린 제트에 비해 높은 것을 확인하였다. 이 효율은 hydrodynamic limit (HL) 미만인 제트인 경우 큰 폭으로 감소하였다. 한편, 시간에 따른 관통량 증분과 제트 소모량의 비교는 SCJ의 이론적인 관통현상 분석을 위해서는 길이 연장 효과를 고려해야함을 보였다.

The organism evaluation equipment (OEE) was developed to determine the insecticidal effect of atmospheric-pressure plasma jets (APPJ). The equipment consisted of a plasma-generating acrylic chamber (PGAC) equipped with a plasma generator, a plasma-maintaining acrylic chamber (PMAC), and plasma efficacy evaluation container (PEEC). The amount of reactive oxygen species (ROS) directly exposed to PEEC in the PMAC was measured using an ozone calculator. The ROS concentration in the PGAC and PEEC increased over time, and the optimum position for the PEEC was selected showing the lowest variance of ROS concentration. Based on the established equipment, five major insect pests (Aphis gossypii, Bemisia tabaci, Helicoverpa armigera, Tetranychus kanzawai, and Thrips palmi) were tested, and their knockdown time, recovery time, and median lethal time (LT50) were determined. As a result, B. tabaci showed the fastest knockdown in respond to the plasma, but the remaining insect pests were knock downed within 2-3 min. Recovery was the fastest in T. palmi and T. kanzawai and slowest in B. tabaci. The LT50 were determined as 13 and 16 min in B. tabaci and T. palmi, respectively. However, the LT50 of other insect pests showed over 21 min. In conclusion, the OEE system can be used to measure the optimum exposure time of plasma against various insect pests, and the plasma might be used as an alternative tools for pest control in the future.