• Journal of the Society of Naval Architects of Korea
• /
• v.60 no.4
• /
• pp.231-239
• /
• 2023

In order to improve the propeller Cavitation Inception Speed (CIS) performance, it needs to modify the propeller geometry and the wake distribution that flows into the propeller. In the previous study, the twisted angles of the V-strut were modified to improve propeller CIS, cavitation behavior and pressure fluctuation performances. Then the propeller behind the modified V-strut (New strut) showed better cavitation characteristics than that behind the existing V-strut (Old strut). However, the CIS of Suction Side Tip Vortex (SSTV) and Pressure Side Tp Vortex (PSTV) showed a big difference at behind each V-strut. In this study, the balance design is conducted to minimize the difference between SSTV CIS and PSTV CIS at behind each V-strut. To improve the propeller CIS performance, 1 propeller is designed at behind the old strut and 3 propellers are designed at behind the new strut. The propeller CIS is increased through the balance design and the stern appendage modification. The final propeller CIS is increased about 5.3 knots higher than that of the existing propeller at behind the old strut. On the basis of the present study, it is thought that the better improvement method for the propeller CIS would be suggested.

• Journal of Chest Surgery
• /
• v.47 no.2
• /
• pp.94-99
• /
• 2014

Background: Surgical repair of a partial anomalous pulmonary venous connection (PAPVC) to the superior vena cava (SVC) may be complicated by sinus node dysfunction or SVC obstruction. We modified the Warden procedure by using a right atrial auricular flap to decrease the occurrence of these complications. Methods: Between February 2005 and July 2012, 10 consecutive patients underwent a modified Warden procedure to correct PAPVC. The median patient age was 5.7 years. Eight patients (80%) had an atrial septal defect. To surgically correct the PAPVC, we made a U-shaped incision on the right atrial appendage and sutured the flap to the posterior wall of the SVC. The anterior wall was reconstructed with various patch materials. Results: No early or late deaths occurred, nor did any patient require early or late reoperation for SVC or pulmonary venous obstruction. No new arrhythmias appeared during follow-up, which was complete in all patients (mean, 29.5 months). Conclusion: Our modification of the Warden procedure seems to be effective and safe. This technique may lower the risk of SVC obstruction, pulmonary venous obstruction, and sinus dysfunction.

• Journal of the Society of Naval Architects of Korea
• /
• v.60 no.1
• /
• pp.1-9
• /
• 2023

In order to improve the propeller cavitation performance composed of Cavitation Inception Speed (CIS), cavitation extent and pressure fluctuation, it needs to improve the wake distribution that flows into the propeller. The warship propeller cavitation is strongly influenced by the wake created at the V-strut of various appendages. The inflow characteristics of the V-strut were investigated using Computational Fluid Dynamics (CFD) and the twisted angles of the V-strut were aligned with upstream flow. The resistance and self-propulsion tests for the model ship with the existing and modified V-struts were conducted in Towing Tank (TT), and wake distribution, CIS, cavitation observation and pressure fluctuation tests were conducted in Large Cavitation Tunnel (LCT). The propeller behind the modified V-strut showed better cavitation characteristics than that behind the existing V-strut. Another model test was conducted to investigate rudder cavitation performance by the change of the V-strut. The rudder cavitation characteristics were not improved by the change of the operating conditions. On the basis of the present study, it is thought that the stern appendages for better propeller cavitation performance would be developed.

• Journal of Ocean Engineering and Technology
• /
• v.24 no.4
• /
• pp.23-31
• /
• 2010

The flow around a remotely-operated vehicle (ROV) has been investigated numerically to improve the resistant performance by modifying the hull form of the ROV. In the case of the base hull form considered in this study, form drag rather than friction drag was the dominant component of total drag. Subsequently, the surfaces that were most susceptible to local pressure effects were modified to give them a more streamlined shape. Eleven different hull forms were chosen to undergo surface modification for drag reduction. In addition, four different boat-tail appendages with different slant angles were installed at the stern to reduce the wake vortices that are induced by the local regions of very low pressure. Consequently, a total of 11 different hull forms for drag reduction were considered. The final hull form, which combined the hull for which surface modification resulted in the lowest drag with a boat-tail appendage with a 15-degree slant angle, resulted in a drag reduction of 20%.