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저면 반사파를 이용한 피로 균열의 정량적 평가에 관한 연구
강승현,이준현,최상우,조윤호 한국비파괴검사학회 2004 학술대회 논문집 Vol.- No.-
Fatigue cracks due to thermal stratification or corrosion in pipelines of nuclear power plants can cause serious problems on reactor cooling system. Therefore, these cracks must be detected before the crack growth to ensure the reliable operation. Ultrasonic techniques have been employed for detecting and sizing these fatigue cracks propagated from the back wall of pipelines. But, it is very difficult to sizing fatigue cracks because of low amplitude of the diffracted tip signal, high noise signal and ultrasound transmission through the closed crack surface. In this study, the signal reflected from the back wall is adopted instead of weak tip signals. In addition, the rate of decrease in amplitude of reflected signals due to reflection at the crack surface and diffraction at the crack tip is used to size fatigue cracks.
저온잠열축열용 TMA 포접화합물에 Ethanol을 첨가한 경우의 냉각특성에 관한 연구
강승현,김광일,정종헌,김창오,김진흥,정낙규 朝鮮大學校 機械技術硏究所 2003 機械技術硏究 Vol.6 No.2
This study aims to improve subcooling and phase change temperature of ThlA clathrate when ethanol is added. The running time of refrigerator is reduced. Also. subcooling and phase change temperature of TMA clathrate are improved. In view of the results achieved the improvement of low temperature thermal storage system is expected.
강승현,윤현규 한국항해항만학회 2014 한국항해항만학회지 Vol.38 No.1
To confirm whether the square tank at Changwon National University (CWNU) can be used for estimation of maneuverability, planar motion mechanism (PMM) test and circular motion (CM) test were performed for various conditions. PMM test can be implemented using an XY carriage and a yaw table in the square tank. However, sometimes test section is insufficient for PMM test owing to low length-breadth ratio of the tank. In addition, the speed of a towing carriage is also quite limited. Therefore, it would be useful if PMM test could be effectively performed diagonally, by establishing coupled control logic to drive three servomotors. In addition, Froude number dependency on the estimated hydrodynamic coefficients was checked. Furthermore, CM tests, which cannot be completed in a conventional linear towing tank, were performed, and its results were compared with the results of PMM test. The results of the PMM tests in the diagonal direction were consistent with the results of the test performed in the direction parallel to the sidewall. However, the results of the CM test were greater than those of the PMM test. This tendency was also observed in the results published at Ulsan University