• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.7
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• pp.652-659
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• 2011

A computational system to predict flowfield and infrared signature in aircraft exhaust system is developed. As the first step, a virtual mission profile is considered and an engine is selected through a performance analysis. Then a nozzle that meets the requirement of each mission is designed. The internal flow in the exhaustion nozzle at the maximum thrust is analyzed using a state-of-the-art CFD code. In addition, a system to combine information of the skin temperature distribution of the nozzle and after-body surface with an infrared prediction code is developed. Finally, qualitative results for the infrared signature reduction design are obtained by investigating the infrared signature level under various conditions.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.4
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• pp.18-24
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• 2014

In this paper, the optimum placement of airborne line-of-sight (LOS) datalink directional antenna to minimize the datalink loss within the operation range of unmanned aerial vehicle (UAV) is analyzed by using the electromagnetic (EM) simulation. In quick banking of UAV, the datalink loss is occurred due to the electromagnetic distortion and transmission loss by the fuselage blockage. In general, the banking angle of UAV is limited to prevent the datalink loss. However, in this case, there is the problem that the mission performance ability is largely limited by the banking radius increase. To solve this problem, the optimum placement to mount the airborne LOS datalink 1-axis directional antenna on both the top and bottom surfaces of fuselage is analyzed by using EM simulation. The 1-axis antenna with large vertical beamwidth is used because the banking angle of UAV is dependent on the vertical beamwidth of antenna. Also, there is the benefit to reduce largely the weight because the 1-axis antenna can be mounted instead of the 2-axis one.

• The Journal of Aerospace Industry
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• s.65
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• pp.70-88
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• 2003

필자가 참여했던 쌍발복합재사업, 쌍발복합재항공기사업, SB427 민수용헬기사업, T-50 초음속고등훈력기 사업을 통해 복합재료의 항공기 적용사례를 고찰하면서, 쌍발복합재항공기는 실험용항공기(Experimental Aircraft)이지만 국내 최초의 전복합재항공기(All-composites Aircraft)로서 항공기 구조물이 순전히 복합재료만을 이용하여 설계 및 제작이 가능하다는 것을 보여주었고, 복합재료를 적용 시 어떠한 이점이 있는지를 보여준 예가 되고 있다. SB427 민수용헬기사업은 헬리콥터에서 로터 블레이드와 동체 등 기체구조물 대분에 왜 복합재료를 사용해야 효과적인 지를 잘 보여주고 있다. SB427 개발 사업을 통해 얻을 수 있는 또 다른 점은 민수용 항공기의 경우 구축된 복합재료 인증체계에 따라 복합재구조물을 개발해야 되고 그래야만 마케팅에서 신뢰를 얻을 수 있다는 것이다. T-50 항공기는 국내에서 최초로 개발된 초음속기로 미익 부문에 복합재료가 응용되었다. 양산 항공기의 주구조물에 복합재료가 쓰인 예는 T-50이 첫 번째 인데 T-50에서 얻어진 복합재 적용기술은 앞으로 개발될 고급 군용기와 민수용기에 널리 활용될 것으로 기대된다. 본 논문에서는, 국내 개발 항공기에서의 복합재료 적용이라는 특정 주제를 중심으로 개발 이력과 기술적 조망을 통하여, 정부, 연구소, 업체 간의 유기적이고 체계적인 전략이 필요하다고 사료되며, 이러한 전략을 바탕으로 효율적인 항공 산업을 선점해야 할 것이다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.11
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• pp.971-977
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• 2015

A numerical analysis for the performance of compound gyroplane in forward flight was performed. TSM(Transient Simulation Method) was used to analyze the performance of autorotating rotor. CFD was conducted for the fuselages to recognize the variation of aerodynamic performance according to flight speed. At given conditions; airspeed, shaft angle and collective pitch, the quasi-static states of autorotation were determined and the variation of rotor performance was observed. Performance analysis results showed that the effect of aerodynamic characteristics in accordance with the shape of fuselage is so important that the streamlined fuselage is essential to fly fast. Forward flight speed limit is dependent on the autorotation performance of rotor.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.6
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• pp.57-63
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• 2005

According to increasing of demand for high accurate and quick measuring technology, they became to interest in industrial photogrammetry that can satisfy with this needs. This study is examined O-2A aircraft to check the application of Industrial Photogrammetry technology. To measure the aircraft alignment, the check points marked on it were used without exact aircraft design data. And to check any deformation of its external original feature, Pro-spot system has been used.

• Proceedings of the Korean Society For Composite Materials Conference
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• 1999.11a
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• pp.246-250
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• 1999

항공기 날개 및 동체의 보강재로 사용되는 스트링거가 압축하중을 받게되면 플렌지와 웹에서의 부분좌굴이 발생하고 이는 좌굴이 발생하지 않은 부분에 과도한 하중이 걸리게 하여 스트링거의 전체적인 하중지지능력을 현저히 감소시킨다. 이러한 손상의 형태가 크리플링(Crippling)이다. (중략)

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.7
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• pp.20-25
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• 2019

In this paper, the structural weakness analysis and quality improvement of small fixed wing UAV of the hard landing type were studied. Unlike conventional aircraft, small UAV does not use runways because of its small size. Instead, small UAV use hand launch takeoff and hard landings. This type has many operational advantages because it can take off and land in a narrow space. But, the hard landing has a strong impact on the structure of the UAV and can cause serious damage. In order to analyze the exact cause of this phenomenon, the structural analysis was carried out using the 3D structural analysis program (ABAQUS) to identify the location of the fracture. And to improve the accuracy of the structural analysis, properties of the material were obtained through specimen test. As a result of the analysis, structural weaknesses were identified and improved. Thus, the validity of the study was verified by demonstrating the quality of enhanced structure through a real impact test at a higher level of 1.5 times the maximum impact during operation.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.20 no.3
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• pp.44-50
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• 2012

The noise reduction is important one of considerations in the process of a civil aircraft development program. External noise sources are classified into an air-born source and a structure-born source. Among these noise sources, the most affected noise source into a cabin is the air-born noise source from an engine or propeller. The external noise is transmitted into the cabin through the fuselage structure of airplane which are composed of an fuselage structure, an interior trim panel and an acoustic insulation layer between an fuselage structure and an interior trim panel. Therefore, appropriate fuselage structure and acoustic insulation layer is very important to reduce the internal noise level. In this paper, the vibro-acoustic coupled analysis of the cabin noise of the 80~90 seats regional turboprop aircraft is carried out to validate the acoustic analysis method using Direct BEM and FEM. The sound pressure level onto the fuselage skin is acquired by fan-source noise analysis using BEM, and which sound pressure is used as acoustic noise source in vibro-acoustic noise analysis for cabin noise analysis using FEM.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.1
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• pp.41-48
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• 2019

This paper deals with a method of aligning an aircraft fuselage and an inertial navigation sensor using three-dimensional coordinates obtained by an optical method. In order to verify the feasibility, we introduce the method to accurately align the coordinate system of the inertial navigation sensor and the aircraft reference coordinate system. It is verified through simulation that reflects the error level of the measuring device. In addition, optimization method based alignment algorithm is proposed for connection between optical sensor and inertial navigation sensor.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.692-697
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• 2005

A canard type aircraft, which has good wing stall and stall/spin proof characteristics, is being developed. The previous first and second prototypes, having full depth core sandwich type wing and fixed landing gear, was built for test flights. Newly developing Firefly will be equipped with retractable landing gear and conventional foam core sandwich laminate for wing and fuselage. For manufacturing, composite material process has been studied including coupon tests. Wet lay-up onto foam core with glass fabric using lay-up mold has been chosen, and composite material parts are cured under room temperature and atmospheric pressure condition. In general, molded parts show so good surface smoothness and standardized quality that are best in mass production. In this study, we present the mold technology and development status for small aircraft firefly.