• 한국항공우주학회지
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• 제40권5호
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• pp.413-422
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• 2012

덕티드팬을 추진 장치로 사용하는 소형 무인항공기는 도심 및 협소한 공간에서 정찰 및 감시에 사용 가능하며, 프로펠러에 비해 높은 추진 효율과 추력 특성을 나타낸다. 덕티드팬 무인항공기의 운용 거리와 비행 시간을 증가시키기 위해서는 정지 비행 및 전진 비행시의 추력 특성연구가 중요하며 비행 안정성 확보를 위해서는 비정상 3차원 유동 특성 연구가 필수적이다. 본 연구에서는 동익과 정익으로 구성된 덕티드팬의 설계 결과 검증과 안정적인 비행 특성을 확인하기 위해 덕티드팬의 추력 특성과 비정상 3차원 유동장을 계측하였다. 덕티드팬의 정지 및 전진 비행시의 추력 특성은 소형 아음속 풍동의 6분력 밸런스 시스템을 이용하여 측정되었고, 비정상 3차원 유동장은 $45^{\circ}$ 경사열선의 프로브 고정법에 의해 분석되었다. 덕티드팬의 덕트와 정익이 추력특성에 다소 큰 영향을 미치며, 정익에 의해 덕티드팬의 안정적인 비행이 가능함을 확인하였다.

• 한국항공운항학회지
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• 제28권2호
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• pp.12-17
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• 2020

Even though the benefit of flight at high angle-of-attack is to be able to reduce the speed of flight and maneuvers in complex flight environment, the flight at high angle-of-attack, however, is easy to be in stall which is characterized by sever unsteady flow separation over an airfoil. Current unsteady numerical analysis using DES was conducted to predict the aerodynamic characteristics of a NACA 0021 airfoil at high angle-of-attack conditions. And this provides the comparison with the steady numerical one with the typical turbulence models. The unsteady calculation by DES is appropriate in terms of predicting the aerodynamic performance of NACA 0021 airfoil at high angle-of-attack conditions.

• 한국군사과학기술학회지
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• 제4권2호
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• pp.30-41
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• 2001

In Underwater Flight Vehicle depth control system, the followings must be required. First, It needs a robust performance which can get over the nonlinear characteristics due to hull shape. Second, It needs an accurate performance which has the small overshoot phenomenon and steady state error to avoid colliding with ground surface and obstacles. Third, It needs a continuous control input to reduce the acoustic noise. Finally, It needs an effective interpolation method which can reduce the dependency of control parameters on speed. To solve these problems, we propose a Intelligence depth control method using Fuzzy Sliding Mode Controller and Neural Network Interpolator. Simulation results show the proposed control scheme has robust and accurate performance by continuous control input and has no speed dependency problem.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1441-1445
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• 2008

Insect flight is adapted to cope with each circumstance by controlling a variety of the parameters of wing motion in nature. Many researchers have struggled to solve the fundamental concept of insect flight, but it has not been solved yet clearly. In this study, to find the most effective flapping wing kinematics, we conducted to analyze CFD data on fixing some of the optimal parameters of wing motion such as stoke amplitude, flip duration and wing rotation type and then controlled the deviation angle by fabricating wing tip motion. Although all patterns have the similar value of lift coefficient and drag coefficient, pattern A(pear-shape type) indicates the highest lift coefficient and pattern H(pear-shape type) has the lowest lift coefficient among four wing tip motions and three deviation angles. This result suggest that the lift and drag coefficient depends on the angle of attack and the deviation angle combined, and it could be explained by delayed stall effect.

• International Journal of Aeronautical and Space Sciences
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• 제5권1호
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• pp.75-82
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• 2004

Nowadays, many kinds of research for airship have being studied withincrease of interests in airship. But these make little progress even now. In flighttest, the data acquisition from the actual flight test has lots of difficulties becausethe airship dynamic response is slow and sensitive to extemal environment. In thispaper, through the actual flight test, appropriateness of the mathematical dynamicmodel was presented by showing the test results in various conditions. Thetuming, the acceleration, and the deceleration motions were tested and analyzed.

• 한국군사과학기술학회지
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• 제9권2호
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• pp.34-41
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• 2006

This paper describes the general considerations and operational applications of aircraft night vision goggle(NVG). The operators should recognize the NVG characteristics, natural night light sources and interoperability between them. And they have to keep attention to the method to take steps to avoid misperceptions, illusions during flight, and the negative impact on the effectiveness and safety of the mission. The considerations based on the interoperability between NVG and night operation suggest the evaluation items of NVG field test and flight test.

• 한국군사과학기술학회지
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• 제13권4호
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• pp.534-541
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• 2010

With the financial sponsorship of FKI and six other companies, the design and construction of the human powered aircraft Sky Runner has been begun to design in December of 2008. And it flew in late December of 2009. The original design configuration was continuously modified in response to test results as a 30.36m span, $35.25m^2$ wing area, 26.0 aspect ratio and 39.8kg of empty weight. Although, we have made only 150m flight flying a few seconds so far however, it will contribute to the research of ultra-light and long duration flying planes. A brief review of some design features, wing layout, prop design, fabrication and flight test results are presented.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2001년도 제33회 춘계학술대회 개최
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• pp.248-256
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• 2001

Capacities of screw are pumping, steady flow of polymer melts, volumetric efficiency, steady volumetric throughout etc. they are affected by geometry of screw, heat flux, pressure on inside barrel, rotating velocity, friction coefficient at screw surface etc. Also the temperature of polymer melts by heating pad and injection pressure play a very important role in the injection molding machine. by computation volumetric efficiency increases as rotating velocity increases, flight number increses, and decreases as friction coefficient increases. but volumetric throughout is different :s flight number increases with helix angle variability. so in this paper we analyze thermal distortion and stress of screw includes pressure and temperature distributions by finite element analysis to understand what design factors influence on thermo-mechanical characteristics of screw.

• International Journal of Aeronautical and Space Sciences
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• 제15권4호
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• pp.356-365
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• 2014

This paper is the second in a series and aims to build a high-fidelity mathematical model for a propeller-driven airplane using the propeller's aerodynamics and inertial models, as developed in the first paper. It focuses on aerodynamic models for the fuselage, the main wing, and the stabilizers under the influence of the wake trailed from the propeller. For this, application of the vortex lattice method is proposed to reflect the propeller's wake effect on those aerodynamic surfaces. By considering the maneuvering flight states and the flow field generated by the propeller wake, the induced velocity at any point on the aerodynamic surfaces can be computed for general flight conditions. Thus, strip theory is well suited to predict the distribution of air loads over wing components and the viscous flow effect can be duly considered using the 2D aerodynamic coefficients for the airfoils used in each wing. These approaches are implemented in building a high-fidelity mathematical model for a propeller-driven airplane. Flight dynamic analysis modules for the trim, linearization, and simulation analyses were developed using the proposed techniques. The flight test results for a series of maneuvering flights with a scaled model were used for comparison with those obtained using the flight dynamics analysis modules to validate the usefulness of the present approaches. The resulting good correlations between the two data sets demonstrate that the flight characteristics of the propeller-driven airplane can be analyzed effectively through the integrated framework with the propeller and airframe aerodynamic models proposed in this study.

• 한국항공운항학회지
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• 제23권1호
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• pp.30-40
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• 2015

Recently, the need of RPA(Remotely Piloted Aircraft) pilots is increasing rapidly with many requirements in order to be a beginner RPA pilot, including basic flight training, instrument flight qualification training, and aircraft type switching training. When RPA pilot gets disqualified, there will be generated much waste of efforts and expenses of trainees those pilots who are disqualified. Therefore, the methodology of pre-verifying those pilots who are not proper as RPA pilots through various scientific methods will save time and expenses with pre-reducing the pilots who will get disqualified later on. The methodology of aptitude test of RPA pilots is laid out as a consideration of pre-study of RPA pilots work analysis, and select types of aptitude test. A suitability of aptitude test is verified. In order to diagnose the flight aptitude precisely, it requires to be developed. Flight aptitude test tools might be connected with training program which could foster piloting aptitude with pre-diagnosing RPA pilot trainee selecting process. For that reason, we made an experiment in order to verify credibility and suitability of these selected programs with developing RPA pilot aptitude test tools. And also, we analyzed relationships among characteristics, analysis of data, and variables to verify the efficiency of data from prior experiment. Through this thesis, we expect to raise efficiency of flight training by providing pre-flight aptitude test information of RPA pilots.