This paper is about improvements to prevent the crack on welding parts of bleed air duct and vent tube in Advanced Trainer ECS owing to vibration. The configurations and the path of vent tube should be changed to prevent the crack. To assure the result of improvements, measured the status of each pressure condition attaching pressure censers on duct and vent tube. The result of life analysis shows that a crack does not happen on improved configuration while a crack initiates after 19th flight and thru cracking could happen after the 30th flight on previous configuration.

20mm Vulcan is one of the representative weapon system that widely operated in army, navy and airforce in Korea. But unstable power which is caused by bad battery cells or insufficiently charged battery box has often caused malfunctions when Vulcan barrel is working. This paper is about improvements of maintenability of APS which is used charging the battery box. The main improvement effects are as follows. First, Break-down of the Power Transistors(PT-8502) inside APS can be prevented by limiting over–current. Second, Automatic charging the battery box is possible by using Micro Controller Unit and SSR. Third, The charging status of battery box can be checked and deficient battery cells recognized by adding LED.

Tracked vehicles for military application such as tank and armored vehicle are operated in severe conditions of driving on gravel road and muddy water including river-crossing. Thus, coating on such vehicles requires more robust characteristics of coating in adhesion, corrosion(salt-spray) resistance and water resistance than those of vehicles for civil applications. Currently, coatings applied on the military equipments are mostly based on the U.S. military specification(known as Mil-SPEC). Typical specifications for primer materials for military application are MIL-P-23377 and MIL-P-53022. And for topcoat, coating material of KDS 8010-1004 specification is typically applied. However, as MIL-P-23377 or MIL-P-530224 is applied for primer coating not only on the tank and armored vehicle at system level but also on the sub-components of these equipments, there has been a need for test data for determining the feasibility of alternatively applying either of these two coatings for primer coat. Therefore, in this study, coating characteristics are compared with respect to these two different primer coating materials so that the feasibility of alternatively applying them is investigated.