• International Journal of Railway
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• v.4 no.2
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• pp.42-49
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• 2011

Today, rolling stock has become a fast and convenient mode of transportation and has witnessed increased demand. But the speed improvement has resulted in increased aerodynamic noise and therefore residential districts near the railroad tracks are exposed to ever increasing noise level. A study on methodologies for measuring and appraising rolling stock's environmental noise has therefore become an important area of endeavor. In the case of the environmental noise, there are no changes in tone so prediction can be made by reducing areas around the railway. The present study explores estimation of the noise around the railway using scale model, and the source of the noise has been investigated as well. The scale model of rolling stock will have to be able to measure high frequency noise and it is required to be generated in a short amount of time. Since popping a balloon or firing a gun fits this requirement the present study analyzed the characteristics of these two different noise sources. Measurement was made in a large vacant lot and the reflection due to the ground was also examined. The method proposed here can be used in the future for predicting the environmental noise of railway vehicles.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.38 no.3
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• pp.108-116
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• 2015

A missile defense system is composed of radars detecting incoming missiles aiming at defense assets, command control units making the decisions on weapon target assignment, and artillery batteries firing of defensive weapons to the incoming missiles. Although, the technology behind the development of radars and weapons is very important, effective assignment of the weapons against missile threats is much more crucial. When incoming missile targets toward valuable assets in the defense area are detected, the asset-based weapon target assignment model addresses the issue of weapon assignment to these missiles so as to maximize the total value of surviving assets threatened by them. In this paper, we present a model for an asset-based weapon assignment problem with shoot-look-shoot engagement policy and fixed set-up time between each anti-missile launch from each defense unit. Then, we show detailed linear approximation process for nonlinear portions of the model and propose final linear approximation model. After that, the proposed model is applied to several ballistic missile defense scenarios. In each defense scenario, the number of incoming missiles, the speed and the position of each missile, the number of defense artillery battery, the number of anti-missile in each artillery battery, single shot kill probability of each weapon to each target, value of assets, the air defense coverage are given. After running lpSolveAPI package of R language with the given data in each scenario in a personal computer, we summarize its weapon target assignment results specified with launch order time for each artillery battery. We also show computer processing time to get the result for each scenario.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.8
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• pp.147-153
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• 2020

Developments in aircraft require safety verification through flight testing for many hours with prototype design and production. The test evaluation step of performing flight tests was an important process that determines the success in the development of the system. In particular, safety development through flight tests in the armed flight test is important for the development of attack helicopters. In the development of attack helicopters, the evaluation period and cost related to the armed flight test are closely related to the required ammunition requirement. Therefore, this paper presents the amount of ammunition required for the military flight test between attack helicopter developments through an analysis of the AH-1 helicopter in a similar case and ADS-44-HDBK of military specification. The AH-1 can be used to calculate the ammunition demand by considering the exclusion of redundant firing tests and configuration differences. In the case of the machine gun-equipped configuration, approximately 10,500R was required, and approximately 324R was required in the case of a rocket-mounted configuration. In addition, if the armed integrated bench is used properly, it is expected to promote efficiently the flight test in the armed flight by identifying the possible risk factors with armed flight tests and excluding them.