A universal joint is a device that transmits the power of a combat vehicle engine to a cooling fan. The power of the engine is transmitted to the universal joint as it is without buffering, and play occurs at the joint between the drive shaft connected to the engine and the driven shaft connected to the cooling fan according to the usage time. Accordingly, the universal joint is periodically replaced, and the criterion for this is the degree of torsion of the universal joint. However, if the universal joint is not properly maintained during the replacement cycle, damage to the universal joint as well as damage to the surrounding power supply may occur. Accordingly, a backlash measuring device was developed to determine the limit of durability of the universal joint, and the limit of durability was derived through regression analysis of the backlash value according to the use time obtained from the accelerated life test.

Most of automobile steering parts are manufactured through the multi-stage cold forging process using round-bar drawn materials. The same process is applied to the ball stud parts of the outer ball joint, and various research activities are being carried out to reduce the extreme manufacturing cost in order to survive in the limitless competition. In this paper, we present a quantitative prediction method for the limiting life of the die as a method for cost reduction in the multi-stage cold forging process. The load on the die was minimized by distributing the forming load based on process optimization through finite element analysis. In addition, based on the quantitative prediction algorithm of the limiting life of the die, the application of the split die and the optimization of the phosphate treatment of the material surface are presented as a conclusion as a method to improve the limiting life of the die.

본 연구에서는 월성 중₩저준위방사성폐기물 처분시설의 내구성 및 한계수명을 예측하였다. 처분시설은 6개의 사일로로 구 성되어 있으며 지하수 포화대에 위치하고 있어 주변 지하수와 화학적 침식 등에 의한 열화에 노출되어 있으며, 장시간이 흐 르면 수리적 방벽으로서의 역할을 상실할 것으로 예상된다. 각각의 인자에 대한 열화시간을 평가한 결과 황산염 및 마그네 슘에 의한 콘크리트 열화속도는 1.308×10-3 cm/yr로 48,000 년 이상인 것으로 나타났으며, 수산화칼슘 침출에 의한 영향은 1,000 년의 기간 경과에서 수산화칼슘 유출 깊이는 1.5 cm이하로 상당히 오랜 시간이 소요되는 것으로 나타났다. 마지막으 로 염해에 의한 철근 부식의 경우 철근 부식개시기간이 1,648 년으로, 최종적으로 구조물이 한계수명 상태에 도달하는 시간 은 2,288 년인 것으로 예측되어 가장 민감한 인자로 평가되었다.