• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.8
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• pp.806-812
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• 2010

Fuel tanks for rotorcraft have a great influence on the survivability of crews. The philosophy of crashworthy rotorcraft design evolved from the long term effort of the US Army. US army established MIL-DTL-27422D for specifying detail requirements related to crash resistant fuel tank especially for military rotorcraft to prevent post crash fire which is the greatest threat to life in rotorcraft crash. Crashworthiness of the rotorcraft fuel tank could be guaranteed through the crash impact tests which are specified in the MIL-DTL-27422D. Fuel tanks for Korea Helicopter Program have been developed and tested according to MIL-DTL-27422D with minor modifications of flexible fittings. The present study shows some results of the mandatory crash impact tests of the fuel tanks to verify their performances.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.15 no.4
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• pp.567-578
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• 2002

The main purpose of this study is to investigate the dynamic behaviour of containment building in nuclear power plant excited by aircraft impact loading using a lower order 8-node solid element. The yield and failure surfaces for concrete material model is formulated on the basis of Drucker-Prager yield criteria and are assumed to be varied by taking account of the visco-plastic energy dissipation. The standard 8-node solid element has prone to exhibit the element deficiencies and the so-called B bar method proposed by Hughes is therefore adopted in this study. The implicit Newmark method is adopted to ensure the numerical stability during the analysis. Finally, the effect of different levels of cracking strain and several types of aircraft loading are examined on the dynamic behaviour of containment building and the results are quantitatively summarized as a future benchmark.

• Journal of Aerospace System Engineering
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• v.16 no.1
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• pp.28-39
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• 2022

With the development of small multicopter PAV (Personal Air Vehicle), it is necessary to develop safety-related devices for manned rotorcraft. In this study, we assumed that an external airbag can be installed in a small multicopter PAV, and using LS-DYNA's Airbag Folding Application, we performed a free-fall collision analysis by modeling the airbag shapes consisting or Roll, Zigzag, and Sigma. There was no significant difference in the final airbag deployment time of the three models. However, when it collides with the ground during deployment, the Sigma fold type external airbag had the fastest deployment speed, applying the most impact force to the PAV, while the Roll fold type external airbag applied the smallest impact force to the PAV.

• Composites Research
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• v.22 no.2
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• pp.18-23
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• 2009

Failure of Kevlar29/Phenolic composite plate under high velocity impact of FSP(Fragment Simulation Projectile) is investigated using a non-linear explicit finite element code, LS-DYNA. Composite laminate and impactor are idealized by solid element and interface between laminas are modeled by tied-break element in LS-DYNA. Interaction between impactor and laminate is simulated face-to-face eroding contact algorithm. When the stress level meets a failure criteria, the layer in the element is eroded. Numerical results are verified by existing test results.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.5
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• pp.110-116
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• 2003

With the growth of aircraft performance and needs for light aircraft, the problems associated with hail impacts on aircraft during flights and grounding become and important issue. These hail encounters can cause severe damages to aircraft and result in major concerns in safety and cost. Since nearly all external components of the commercial and military aircraft-in particular, the nose section and the leading edge of the wing and tail-are subject to damages, much effort has been put into understanding of this problem. However, most of the previous studies have focused on the composite components and few results have been reported for the metallic components. In this paper, we study the ice impacts on the aluminum component with the finite element analysis method utilizing commercial non-linear dynamics solver LS-DYNA. The results are compared with the experimental data and a simple measure of the ice impact effects is proposed.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.11
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• pp.35-41
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• 2006

This paper proposes an algorithm for switching LQ(Linear Quadratic) controllers designed at each flight envelope without a bump phenomenon. This algorithm is derived to apply to LQ controller more easily than existing implementation algorithm and is proposed to consider trim points of nonlinear models, which is adequate to real applications. This paper exemplifies the control performance improvement via simulations applied to LQ control of a supersonic test aircraft as a benchmark problem to test the proposed algorithm performance.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.19 no.2
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• pp.69-74
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• 2023

The paper presents the results investigating the effect of aircraft engine impact location on the intended function evaluation results of spent nuclear fuel transport cask. As a result of the investigation, it is found that the structural integrity is maintained as the maximum accumulated equivalent plastic strain is below the acceptable criterion regardless of the collision location. It is identified that when the aircraft engine collided with the upper part of the transport cask without considering impact limiter the containment performance is weakened compared to when the aircraft engine collided with the central part.

• 한국항공운항학회:학술대회논문집
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• 2004.11a
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• pp.247-252
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• 2004

민항기나 군용항공기의 경우 대부분 항행 안전성을 확보하기 위해 다양한 기능을 수행하는 레이다가 부착되어 있으나, 소형항공기 및 저가의 헬기의 경우 무게, 비용 등의 제약으로 항행 안전을 확보할 수 있는 레이다가 장착되어 있지 않는 실정이다. 따라서 본 연구에서는 민항기 및 군용 항공기뿐만이 아니라 헬기 및 소형항공기에 장착하여 충돌감지, 이착륙보조, 기상관측 등의 기능을 수행할 수 있는 레이다로 35GHz 밀리미터 대역의 항공기 탑재형 레이다의 적용에 대한 제반 요건과 필요성에 대한 연구를 수행하였다. 그리고 제안된 레이다를 이용하면, 저속 항공기 및 헬기에서는 치명적인 사고를 유발시킬 수 있는 전력선 탐지가 가능함을 확인함으로써, 제안된 레이다가 항행 안전성을 높일 수 있음을 보임으로써 밀리미터 대역 레이다의 적용이 가능함을 확인하였다.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2011.05a
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• pp.33-34
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• 2011

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.6
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• pp.419-429
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• 2020

In conducting a mission to explore and track targets using a number of unmanned aerial vehicles(UAVs), performance for that mission may vary significantly depending on the operating conditions of the UAVs such as the number of operations, the altitude, and what future flight paths each aircraft decides based on its current position. However, studies on the number of operations, operating conditions, and flight patterns of unmanned aircraft in these surveillance missions are insufficient. In this study, several types of flight simulations were conducted to detect and determine targets while multiple UAVs were involved in the avoidance of collisions according to various autonomous flight algorithms based by flocking theory, and the results were presented to suggest a more efficient/effective way to control a number of UAVs in target detection missions.