• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.7
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• pp.642-652
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• 2009

Most of lap jointed aircraft structures encounter the fretting damages, which provoke fretting cracks prematurely and lead to significant reduction of fatigue life. In the case of ageing aircrafts especially, this fretting fatigue problem is a fatal threat for the safety and airworthiness. Recently, as the service life extension program(SLEP) of ageing aircrafts has become a hot issue, the prediction of fretting fatigue life is also indispensable. On these backgrounds, a series of experimental tests of fretting fatigue on bolted lap joint specimens, were performed. And the fretting crack initiation and propagation life of each specimen were evaluated using existing and newly proposed prediction models with the fretting parameters obtained from the FEA results for elasto-plastic contact stress analyses. The validations of prediction models were also discussed, comparing the prediction results with experimental test ones.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.6
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• pp.481-489
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• 2017

Situation awareness means recognizing everything necessary to understand progress in a flight or aircraft maintenance work. Situation awareness is based on more than simply recognizing important about the environment, and it is important to provide the meaning of information in an integrated form. The KHP provides the pilot with integrated situation display for an integrated form of situation awareness and warning that synchronizes the priority based audible signal with the visual signal. Provide integrated display and warning to reduce operator error and enable operators to focus on mission critical tasks and events. This paper introduces the integrated situation display and warning design implemented in the KHP.

• International Journal of Aeronautical and Space Sciences
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• v.10 no.2
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• pp.117-124
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• 2009

In the environment where various and complicated threat signals exist, RWR (Radar Warning Receiver), which can warn pilot of the existence of threats, has long been a necessary electronic warfare (EW) system to improve survivability of aircraft. The angle of arrival (AOA) information, the most reliable sorting parameter in the RWR, is measured by means of four-quadrant amplitude comparison direction finding (DF) technique. Each of four antennas (usually spiral antenna) of DF unit covers one of four quadrant zones, with 90 degrees apart with nearby antenna. According to the location of antenna installed in helicopter, RWR is subject to signal loss and interference by helicopter body and structures including tail bumper, rotor blade, and so on, causing a difficulty of detecting hostile emitters. In this paper, the performance degradation caused by signal interference by tail rotor blades has been estimated by measuring amplitude video signals into which RWR converts RF signals in case a part of antenna is screened by real tail rotor blade in anechoic chamber. The results show that corruption of pulse amplitude (PA) is main cause of DF error. We have proposed two algorithms for resolving the interference by tail rotor blades as below: First, expand the AOA group range for pulse grouping at the first signal analysis phase. Second, merge each of pulse trains with the other, that signal parameter except PRI and AOA is similar, after the first signal analysis phase. The presented method makes it possible to use RWR by reducing interference caused by blade screening in case antenna is screened by tail rotor blades.

• 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 Korean Society for Aeronautical & Space Sciences
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• v.40 no.9
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• pp.760-770
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• 2012

In order to provide precision approach service based on GBAS, air navigation service providers should validate the GBAS system performance against international standard requirements and receive approval. The GBAS manufacturer should define integrity threat, analyze the integrity monitors and evaluate performance of the implemented monitors to verify integrity performance which is critical to the aircraft safety. This paper describes a statistical test result to evaluate performance of the code carrier divergence monitors implemented in KARI Integrity Monitor System software. The paper introduces analysis and test procedure which is developed for the performance evaluation and describes the analysis, the test scenario generation and the test results. The results show that the implemented monitors can detect the expected minimum detectable errors with satisfying the probability of missed detection requirements.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.3
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• pp.242-253
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• 2011

The typical missions for the current stand-off UAVs are surveillance and reconnaissance. On the other hand, the primary mission for the future UCAS will be combat mission such as SEAD under the man-made ultimately hostile environment including SAM, antiaircraft artillery, threat radar, etc. Therefore, one of the most important challenges in UCAS design is improvement of survivability. The current studies for aircraft combat survivability are focused on the improvement of susceptibility and vulnerability of manned aircraft system. Although the survivability design methodology for UCAS might be very similar to the manned combat system but there are some differences in mission environment, system configuration, performance between manned and unmanned systems. So the parameters and their sensitivities which affect aircraft combat survivability are different in qualitatively and quantitatively. The susceptibility related parameters for F-16 C/D and X-45A as an example of manned and unmanned system are identified and the susceptibility parameter sensitivities are analyzed by using Monte-Carlo Simulation in this study.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.12
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• pp.856-864
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• 2019

The weapon-target assignment (WTA) problem is a matter of effectively allocating weapons to a number of threats. The WTA in a rapidly changing dynamic environment of engagement must take into account both of properties of the threat and the weapon and the effect of the previous decision. We propose a method of applying the Greedy Randomized Adaptive Search Procedure (GRASP) algorithm, a kind of meta-heuristic method, to derive optimal solution for a dynamic WTA problem. Firstly, we define a dynamic WTA problem and formulate a mathematical model for applying the algorithm. For the purpose of the assignment strategy, the objective function is defined and time-varying constraints are considered. The dynamic WTA problem is then solved by applying the GRASP algorithm. The optimal solution characteristics of the formalized dynamic WTA problem are analyzed through the simulation, and the algorithm performance is verified via the Monte-Carlo simulation.

• The Korean Journal of Air & Space Law and Policy
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• v.33 no.2
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• pp.199-224
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• 2018

Aviation's safety record continues to improve yearly, especially with respect to passenger and crew injuries and deaths. However, although the number of accidents has decreased over the decades, there are still many events, such as landings short of the runway and runway excursions, both of which pose threats to passenger and crew safety. Surviving any kind of aviation accident depends on the physiological threat and stress of the impact(s), the extent to which the physical structure surrounding the passengers and crew remains intact, and the ability of the passengers and crew to be able to escape the wreckage. The one action that both passengers and crew can carry out to help decrease the likelihood of crash-related injury or death is to assume an emergency brace position. Doing so has been demonstrated over several decades to improve survivability. While cabin crew are taught (and then might have to teach passengers in an emergency about the emergency brace position), passengers in many parts of the world never learn about the brace position unless they are involved in an emergency in which there is time to prepare for the landing. This lack of provision of information is related to the fact that most airlines do not provide information in the preflight safety briefing and some do not even provide the information in the passenger safety cards. Many countries do not require their airlines to do so, a fact, which in turn, is related to the lack of mention of the brace position in ICAO's Annex 6. Until standards and recommended practices are changed at the highest world level, passengers will continue to be deprived of this vital, life-saving information that they can use, potentially to help save their own lives.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.12
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• pp.971-980
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• 2021

Recently popularized drone technologies have revealed that low-cost small unmanned aerial vehicles(UAVs) can be a significant threat to prevailing power by operating in group or in swarms. Researchers in many countries have tried to utilize integrated swarm unmanned aerial system(SUAS) in the battlefield. Agency for Defense Development also identified four core technologies in developing SUAS: swarm control, swarm network, swarm information, and swarm collaboration, and the authors started researches on swarm control and network technologies in order to be able to operate vehicle platforms as the first stage. This paper introduces design and integration of SUAS consisting of small fixed-wing UAVs, swarm control and network algorithms, a ground control system, and a launcher, with which swarm control and network technologies have been verified by flight tests. 19 fixed-wing UAVs succeeded in swarm flight in the final flight test for the first time as a domestic research.

• Convergence Security Journal
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• v.22 no.1
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• pp.129-134
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• 2022

A smart platform is defined as an evolved platform that realizes physical and virtual space into a hyper-connected environment by combining the existing platform and advanced IT technology. The hyper-connection that is the connection between information and information, infrastructure and infrastructure, infrastructure and information, or space and service, enables the realization and provision of high-quality services that significantly change the quality of life and environment of users. In addition, it is providing everyone with the effect of significantly improving the social safety net and personal health management level by implementing smart government and smart healthcare. A lot of information produced and consumed in these processes can act as a factor threatening the basic rights of the public and individuals by the informations themselves or through big data analysis. In particular, as the smart platform as a core function that forms the ecosystem of a smart city is naturally and continuously expanded, it faces a huge security burden in data processing and network operation. In this paper, platform components as core functions of smart city and appropriate security threats and countermeasures are studied.