• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.10
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• pp.840-848
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• 2013

Airworthiness certification of military aircraft is a government's certification that it must have airworthiness and ability to demonstrate its requested function and performance. NATO released STANAG-4671 to establish the minimum airworthiness requirements for UAVs between 150kg and 20,000kg MTOW in 2009. Up to now, there are no clear airworthiness certification criteria and guideline for small UAV which is less than 150kg. STANAG-4671 is used for military UAV airworthiness certification in Korea as Other Airworthiness Certification Criteria. However, since STANAG-4671 requires the same Target Level of Safety without regard to MTOW, excessive Target Level of Safety or design requirements could be applied to relatively small-medium UAV. In this paper, classification and criteria of airworthiness certification for military UAV were investigated and a Target Level of Safety was analyzed based on MTOW using ground victim criteria.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.6
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• pp.478-487
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• 2014

The simplified performance analysis and initial configuration design are required for the successful development of UAV during the conceptual design, in which empirical formulas and trend equations are utilized for the UAV performance analysis. In the conceptual design phase various UAV configurations may be considered, however, it is very inefficient and unnecessary to consider all configurations for the conceptual design. In this study, the database for the fixed wing UAVs whose MTOW is between 50kg and 1,500kg was also constructed for the selection of configuration frequently used. The parametric analyses were performed for major performance parameters, and trend equations were developed through regression analyses for these individual performance parameters.

• Journal of Aerospace System Engineering
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• v.13 no.3
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• pp.56-63
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• 2019

Performance analyses were performed on a propeller developed for use in a PAV (Personal Air Vehicle) under 600 kg Maximum Take-Off Weight (MTOW). The actuator disc theory and CFD analyses were used to estimate the hovering time with regards to MTOW variation for a given battery weight. The interference induced power factor kint was introduced to account for the effect of flow interference between the propellers and to estimate the performance of counter-rotating propellers. The Maximum Figure of Merit (FM) value of the propeller pitch was determined and the design RPM range for the required power inversely obtained from the CFD results. Previous research indicate that the flight time of large multi-copter is limited by the available battery energy density. Similarly, the propeller pitch settings and spacing are important factors in reducing the kint value.

• Journal of Advanced Navigation Technology
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• v.27 no.1
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• pp.77-95
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• 2023

In this study, the conceptual design of a tilt + stopped rotor type electric vertical take-off and landing (eVTOL) aircraft was performed using design iteration. Based on Hyundai Motor's S-A1, the mission profile was defined using the concept of urban air mobility (UAM), and configuration design and aerodynamic analysis were performed using OpenVSP and XFLR5 software. After estimating the required power for the designed eVTOL, the required performance of the battery and the maximum take-off weight (MTOW) were calculated. . It was iteratively calculated using Microsoft Excel and Visual Basic Application, and a new electric motor weight estimation formula was derived. Also, the sensitivity analyses of each design variables of an eVTOL was performed using the automated program.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.25 no.2
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• pp.12-17
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• 2017

Manned aircraft structural design is based on structural safety factor of 1.5, and this safety factor is equivalent to a probability of failure of between 10-2 and 10-3. The target failure probability of FARs is between 10-6 and 10-9 per flight according to aircraft type. NATO released STANAG 4703 to established the airworthiness requirements for small UAV which is less than 150kg. STANAG 4703 requires the Target Level of Safety according to MTOW. The requirements of failure probability for small UAV is between 10-4 and 10-5. In this paper, requirements of airworthiness certification for small UAV were investigated and the relationship of safety factors to the probability of structural failure is analyzed to reduce measure of safety factor and structural weight of unmanned aircraft.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.1033-1037
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• 2007

The final purpose of this study is to develop noise abatement procedures for minimizing the environmental impacts caused by aircraft noise in the vicinity of Gimpo Int'l Airport, and to establish appropriate noise limits and monitoring system. The results of study was suggests for more detail the crucial factors which one is reference noise level, $L_{MAX}=88dB(A)$ at 6.5km after take-off, and second one is to installation the additional three(3) noise monitoring system on both side of runway.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.9
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• pp.874-880
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• 2007

The final purpose of this study is to develop noise abatement procedures for minimizing the environmental impacts caused by aircraft noise in the vicinity of Gimpo Int'l Airport, and to establish appropriate noise limits and monitoring system. The results of study was suggests for more detail the crucial factors which one is reference noise level, $L_{MAX}=88 dB(A)$ at 6.5 km after take-off, and second one is to installation the additional three(3) noise monitoring system on both side of runway.

• Journal of Aerospace System Engineering
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• v.14 no.4
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• pp.40-46
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• 2020

Recently, the aviation industry has sought to reduce its carbon usage in aircraft operations. Specifically, the industry is proceeding with the development of ultra-large turbofan engines and the development of hybrid electric engines to reduce the fuel consumption of aircraft. In one case, Airbus is developing as its future goal an aircraft with a short take-off distance that uses a catapult. In this study, when a b747-400 aircraft with two of the four engines removed was tested using a catapult, its fuel consumption was compared with that of the original aircraft. Fuel consumption was calculated using the mass flow consumption formula. Further, the aircraft L/D ratio caused by engine removal was interpreted using the CFD Tool, Ansys Fluent. The results showed that the lift ratio was improved by about 7% and that the fuel efficiency was improved by about 14%.

• Journal of Dental Rehabilitation and Applied Science
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• v.23 no.4
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• pp.293-302
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• 2007

I. Objectives The purpose of this study was to compare the shaping ability between the single length technique performed with Mtwo instruments (VDW, Munich, Germany) and the crown-down technique using K3 (SybronEndo, West Collins, CA, USA) and RaCe (FKG, La Chaux-de-Fonds, Switzerland) instruments. II. Materials & Methods Forty five curved canals in resin blocks were equally divided in to three groups. Group 1 (Mtwo) was instrumented used the full length of canal according to the manufacturer's instructions. The simulated canals was prepared to an instrument size of 35, 0.04 taper canal terminus. In group 2 (Race) and group 3 (K3) was instrumented in a crown-down manner and prepared to an instrument size of 30, 0.06 taper canal terminus. Pre- and post-instrumentation images were scanned and assessment of canal shape was completed with a computer image analysis program. Material removal was measured at 7 measuring points, beginning 1mm from the end point of preparation. Differenced of centering ratio were statistically analyzed using One-way ANOVA followed by Duncan's test. II. Results & Conclusion There was no significant difference on 1, 2, 3 and 7mm measuring point. At 4 and 5 measuring point, significant difference showed between the Mtow instruments and other two instruments. (p<0.05)

• Journal of Aerospace System Engineering
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• v.14 no.spc
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• pp.13-21
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• 2020

RTCA DO-178C is a development guideline to ensure aircraft system airworthiness. However, there is an opinion that the application of DO-178C to the development of UAV of more than MTOW 150 kg is over regulated because the severity of the risk from UAV is lower than that of normal aircraft. To address issue, EASA and FAA have been working on the Re-Engineering and Streamlining the Standards for Avionics Certification(RESSAC) project since 2016 with the goal of establishing a new certification scheme that simplifies existing aircraft certification procedures and standards. This paper analyzes the current DO-178C certification process and presents advantages by comparing and analyzing the new RESSAC certification process, which simplifies processes and outputs in comparing with the DO-178C certification process, while it ensures flight safety of the vehicle.