• Smart Structures and Systems
• /
• 제6권2호
• /
• pp.135-146
• /
• 2010

This paper presents the perspective of the Structural Mechanics program of the Air Force Office of Scientific Research (AFOSR) on the damage assessment of structures for the period 2006-2009 when the author was serving as Program Manager at AFOSR. It is found that damage assessment of structures plays a very important role in assuring the safety and operational readiness of US Air Force fleet. The current fleet has many aging aircraft, which poses a considerable challenge for the operators and maintainers. The nondestructive evaluation technology is rather mature and able to detect damage with considerable reliability during the periodic maintenance inspections. The emerging structural health monitoring methodology has great potential, because it will use on-board damage detection sensors and systems, will be able to offer on-demand structural health bulletins. Considerable fundamental and applied research is still needed to enable the development, implementation, and dissemination of structural health monitoring technology.

• 한국항공우주학회지
• /
• 제36권4호
• /
• pp.368-374
• /
• 2008

국내 독자 기술로 개발된 KT-1/KO-1 기본 훈련기는 멕시코, 필리핀, 터키, 베네주엘라 등 주요 수출 대상국가의 보유 기본 훈련기 및 무장기에 대한 교체 후보 기종으로 주목받고 있다. 본 연구를 통하여 KT-1 해외수출을 확대하기 위해 동급 기종의 경쟁사를 분석 하고 대륙별 기본 훈련기 보유 현황과 Fade Out 시기를 예측하였다. 시장조사 결과 2025년 까지 33개국에 4,500여대의 소요가 예상 되었으며 자국 항공기 경쟁기종 보유, 정치 외교환경, 경제 환경 등의 고려에 의한 마케팅 가능 국가를 선정하여 수출가능 대수를 예측하였다.

• 한국항공운항학회지
• /
• 제16권4호
• /
• pp.41-48
• /
• 2008

Functional analysis of air transport mission is conducted to establish the performance requirements of the commercial transport designs. The analysis process begins by making a top-down analysis to the aircraft system level mission functions. Correctly interpreting the top-level performance requirements is the first step in designing and building an aircraft system. Each function and sub-function is allocated and examined to the aircraft level and flight operations phase to optimize the system performance and design requirements, such that these lower-level requirements can be traced back to the top-level requirements they are designed to fulfill. Special attention is given to making sure all interfaces, both internal and external, are addressed. The results are also in good resources of functional hazard assessment involved in certification processes.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2003년도 ICCAS
• /
• pp.2560-2565
• /
• 2003

The paper presented here covers the work associated with the flight control law design, ground based and in flight simulation and handling qualities assessment of the Fly-by-Wire type Aircraft (FBWA). The control law was designed for the most unstable aircraft configuration flight regime for the target aircraft (FBWA). The ground based simulation including math-model, real-time pilot-in-the-loop and iron bird simulation were used for validation of the control law before the experimental in-flight simulation on the IFS (In.Flight-Simulator) aircraft. The flight tests results showed that Level 1 handling qualities for the most unstable flight regime were achieved.

• Nuclear Engineering and Technology
• /
• 제52권2호
• /
• pp.397-416
• /
• 2020

Investigations of the commercial aircraft impact effect on nuclear island infrastructures have been drawing extensive attention, and this paper aims to perform the safety assessment of Generation III nuclear power plant (NPP) buildings subjected to typical commercial aircrafts crash. At present Part II, based on the verified finite element (FE) models of aircrafts Airbus A320 and A380, as well as the NPP containment and auxiliary buildings in Part I of this paper, the whole collision process is reproduced numerically by adopting the coupled missile-target interaction approach with the finite element code LS-DYNA. The impact induced damage of NPP plant under four impact locations of containment (cylinder, air intake, conical roof and PCS water tank) and two impact locations of auxiliary buildings (exterior wall and roof of spent fuel pool room) are evaluated. Furthermore, by considering the inner structures in the containment and raft foundation of NPP, the structural vibration analyses are conducted under two impact locations (middle height of cylinder, main control room in the auxiliary buildings). It indicates that, within the discussed scenarios, NPP structures can withstand the impact of both two aircrafts, while the functionality of internal equipment on higher floors will be affected to some extent under impact induced vibrations, and A380 aircraft will cause more serious structural damage and vibrations than A320 aircraft. The present work can provide helpful references to assess the safety of the structures and inner equipment of NPP plant under commercial aircraft impact.

• 한국항공우주학회지
• /
• 제41권8호
• /
• pp.619-624
• /
• 2013

확률론적 수명예측은 파라미터들의 불확실성에 대하여 확률론적인 요소를 적용한다. 따라서 기존의 결정론적 수명해석 기법에 확률론적 기법을 적용하기 위해서는 파손확률을 이용한 위험도 평가가 필요하다. 본 연구에서는 항공기 구조물의 확률론적 위험도평가를 수행하기 위하여 파손확률 추정 모델링 기법을 연구하였다. 이를 위해 파라미터들의 확률론적 불확실성을 효과적으로 반영할 수 있는 베이지안 기법을 이용하여 파손확률을 모델링하고 실험 데이터를 이용하여 검증하였다. 연구결과 베이지안 기반의 파손확률 추정 모델링은 정량적인 파손확률을 계산하고 확률론적 위험도평가를 효과적으로 수행할 수 있음을 입증하였다.

• Advances in aircraft and spacecraft science
• /
• 제1권3호
• /
• pp.311-330
• /
• 2014

Environmental impact of aircraft emissions can be addressed in two ways. Air quality impact occurs during landings and takeoffs while in-flight impact during climbs and cruises influences climate change, ozone and UV-radiation. The aim of this paper is to investigate airports related local emissions and fuel consumption (FC). It gives flight path optimization model linked to a dispersion model as well as numerical methods. Operational factors are considered and the cost function integrates objectives taking into account FC and induced pollutant concentrations. We have compared pollutants emitted and their reduction during LTO cycles, optimized flight path and with analysis by Dopelheuer. Pollutants appearing from incomplete and complete combustion processes have been discussed. Because of calculation difficulties, no assessment has been made for the soot, $H_2O$ and $PM_{2.5}$. In addition, because of the low reliability of models quantifying pollutant emissions of the APU, an empirical evaluation has been done. This is based on Benson's fuel flow method. A new model, giving FC and predicting the in-flight emissions, has been developed. It fits with the Boeing FC model. We confirm that FC can be reduced by 3% for takeoffs and 27% for landings. This contributes to analyze the intelligent fuel gauge computing the in-flight fuel flow. Further research is needed to define the role of $NO_x$ which is emitted during the combustion process derived from the ambient air, not the fuel. Models are needed for analyzing the effects of fleet composition and engine combinations on emission factors and fuel flow assessment.

• Nuclear Engineering and Technology
• /
• 제52권2호
• /
• pp.417-428
• /
• 2020

Investigations of the commercial aircraft impact effect on nuclear island infrastructures have been drawing extensive attention, and this paper aims to perform the safety assessment of Generation III nuclear power plant (NPP) buildings subjected to typical commercial aircrafts crash. At present Part III, the local damage of the rigid components of aircraft, e.g., engine and landing gear, impacting the steel concrete (SC) structures of NPP containment is mainly discussed. Two typical SC target panels with the thicknesses of 40 mm and 100 mm, as well as the steel cylindrical projectile with a mass of 2.15 kg and a diameter of 80 mm are fabricated. By using a large-caliber air gas gun, both the projectile penetration and perforation test are conducted, in which the striking velocities were ranged from 96 m/s to 157 m/s. The bulging velocity and the maximal deflection of rear steel plate, as well as penetration depth of projectile are derived, and the local deformation and failure modes of SC panels are assessed experimentally. Then, the commercial finite element program LS-DYNA is utilized to perform the numerical simulations, by comparisons with the experimental and simulated projectile impact process and SC panel damage, the numerical algorithm, constitutive models and the corresponding parameters are verified. The present work can provide helpful references for the evaluation of the local impact resistance of NPP buildings against the aircraft engine.

• 한국군사과학기술학회지
• /
• 제17권1호
• /
• pp.41-49
• /
• 2014

In this paper, we consider a method to access the number of aircraft requirement which is a strategic variable in national security. This problem becomes more important considering the F-X and KF-X project in ROKAF. Traditionally, ATO(Air Tasking Order) and fighting power index have been used to evaluate the number of aircrafts required in ROKAF. However, those methods considers static aspect of aircraft requirement. This paper deals with a model to accommodate dynamic feature of aircraft requirement using absorbing Markov chain. In conclusion, we suggest a dynamic model to evaluate the number of aircrafts required with key decision variables such as destroying rate, failure rate and repair rate.

• 한국항공운항학회지
• /
• 제28권4호
• /
• pp.55-62
• /
• 2020

Special airworthiness certificates can be issued if the aircraft does not meet the airworthiness standards, but it is deemed that it can be operated safely by partially limiting the scope of operation and flight performance. Currently, Korea is subject to experimental special certification for UAS(Unmanned Aircraft Systems) exceeding 150 kg of its own weight, but detailed guidelines need to be prepared on how to prove that they can be operated safely in a limited range. Recently, Korea Airworthiness Standard(KAS) Part 21 has been revised to reflect this, but it needs to be supplemented. In this study, through an understanding and analysis of the FAA's procedure of expeirmental special airworthiness certifications for UAS, we would like to suggest what we should consider when developing relevant guidelines in our country.