• Journal of the Korean Society for Railway
• /
• v.10 no.6
• /
• pp.800-805
• /
• 2007

The critical speed of railway bogie is very important in terms of the verification of the vehicle design procedure and safety. The dynamic performance of bogie is tested on the railway roller rig in a laboratory in place of field testing on track. But, the testing on the full scale roller rig caused many problems relating to test costs, test time and has the difficulty in test condition setup. To overcome these problems, scaled models were used in the filed of railway vehicle design and test. In this paper, we have studied the critical speed of scaled bogie model. We have made the 1/5 scaled bogie, the scaled roller rig and analyzed the critical speed of the scaled bogie through the numerical simulation and running test of the scaled bogie. We have confirmed that the analysis results of the critical speed correspond with the test results.

• Journal of the Korean Society for Railway
• /
• v.15 no.1
• /
• pp.9-16
• /
• 2012

The dynamic stability of railway vehicle has been one of the important issues in railway safety. The dynamic simulator has been used in the study about the dynamic stability of railway vehicle and wheel/rail interface optimization. Especially, a small scale simulator has been widely used in the fundamental study in the laboratory instead of full scale roller rig which is not cost effective and inconvenient to achieve diverse design parameters. But the technique for the design of the small scale simulator about the dynamic characteristics of the wheel-rail system and the bogie system has not been well developed in Korea. Therefore, the research using the small-scaled derailment simulator and the 1/5 scaled bogie has been conducted. In this paper, we did running stability test of 1/5 scaled bogie using small-scaled derailment simulator. Also, for the operation of the small scaled simulator, it is required to investigate the performance and characteristics of the simulator system. This could be achieved by a comparative study between an analysis and an experiment. This paper presented the analytical model which could be used for verifying the test results and understanding of the physical behavior of the dynamic system comprising the small- scaled derailment simulator and the 1/5 scaled bogie.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.23 no.3
• /
• pp.112-118
• /
• 2019

The development of an underwater rocket propulsion system was described in this paper. Throttle able liquid propellant and hybrid rocket propulsion systems were selected for underwater propulsion. A subscale liquid rocket combustion chamber and it's portable stand were developed and their applicability was examined. 1.5-ton.f and 1.8-ton.f hybrid rockets were developed for underwater applications. The test results indicated that the 18-ton.f hybrid rocket fully complies to the performance and underwater cruise stability requirements; thus, its development was concluded to be successfully complete.