• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2000.04a
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• pp.37-37
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• 2000

복합재료는 높은 무게비 강도 및 강성뿐만 아니라 우수한 재료 특성 때문에 경량화와 구조적 안전성이 요구되는 항공기의 구조재로서 사용이 증대되고 있다. 소형 민용항공기는 구조적 안전성과 함께 제작과 정비, 유지보수의 용이성이 중요시된다. 본 연구에서는 복합재료를 구조재로 사용하였을 때의 성능변화와 경량화 등을 검토하기 위하여 기존의 알루미늄 합금을 이용하여 설계된 소형 프로펠러 경항공기 날개의 구조재로서 복합재료를 사용하여 재설계하였다. 날개의 기본 구조는 스킨, 스파, 웹으로 구성된 상자형 단면으로 설계하였으며 날개의 구조재로서 탄소/에폭시를 사용하여 상용 유한요소해석코드인 NISAII를 이용하여 굽힘, 좌굴 등의 응력해석을 수행하였고 기존 설계된 날개와의 성능비교를 위하여 알루미늄 합금으로 설계된 날개를 모델링하여 해석한 결과와 비교하였다. 비교결과 구조재로 탄소/에폭시를 사용하여 설계된 날개가 무게비 성능면에서 더 우수함을 확인하였다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2000.04a
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• pp.38-38
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• 2000

풍력 발전용 회전 날개는 대형화되면서 종래의 목재나 금속재료로는 구조적 강도, 강성 및 피로수명, 경제성 등을 만족하지 못하게 되었고, 이를 보완하기 위해 복합재료의 사용이 불가피하게 되었다. 따라서 본 연구에서는 국내업체에서 생산하여 그 물성이 입증된 E-glass/Epoxy 복합재료를 사용하여 국내 기상조건에 적합한 풍력발전용 회전날개를 개발하였다. 그러나, 개발된 회전날개는 국내 기상조건에 적합하도록 설계된 것으로서 해외로 수출할 경우 국내보다 풍속이 큰 지역에서는 구조적 안정성 및 피로수명을 만족할 수 없게 된다. 즉, 개발된 회전날개의 외국시장 진출을 위해서는 국제규격에 따른 하중의 정의와 구조설계의 개선이 필요하다. 따라서 본 연구에서는 IEC 1400-1의 국제규격을 검토하여 이를 만족하도록 회전날개의 구조설계를 수행하였다. 그 결과 국제규격에 명시된 강도 및 피로수명을 만족하는 구조설계 결과를 얻을 수 있었다.

• Aerospace Engineering and Technology
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• v.10 no.1
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• pp.175-182
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• 2011

Optimized design was performed for a subsonic aircraft wing. The subsonic aircraft is dual turbo-prop and carrying less than 100 passengers. The cruise speed is Mach 0.6. The design was performed by two stages. The first stage is to decide the height of horizontal tail by analyzing the directional stability with Vorstab and then, the optimized wing configuration was selected with Piano, a optimizer commercially available. Fluent, a commercial CFD software was utilized to predict the aerodynamic performance of the aircraft. Drag of the aircraft was minimized with maintaining constant lift for cruise. The optimization reduced 10 counts from the initial wing configuration.

• Journal of Aerospace System Engineering
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• v.12 no.3
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• pp.70-78
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• 2018

This research was carried out to develop an integrated folding wing made from carbon composite materials. Design requirements were reviewed and composite wing sizing was conducted using design optimization with commercial software. Three composite manufacturing processes including hot-press, pultrusion, and autoclave were evaluated and the most suitable processes for the integrated wing fabrication were selected, with consideration given to performance and cost. The determined manufacturing process was verified by two design development tests for selecting the design concept. Stiffness and strength of the composite wing were estimated through structural analyses. The test loads were calculated and static tests about design limit load and design ultimate load were performed using both wings. As a result, the evaluation criterions of the tests were satisfied and structural safety was verified through the series of structural analyses and testing.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.3A
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• pp.145-152
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• 2011

Current Bridge Specification for Highway Bridges adopts a simplified method to determine sectional forces of abutment wing by dividing its area into four sections. This simplified method was developed in Japan when numerical analysis was not mature and computer resources were expensive. This simplified method has been with us without modification. This study evaluates the problem of current design practice to improve the design guideline for abutment wing. In this study, a finite element model of abutment wing based on shell elements was developed to obtain accurate sectional force. In addition, foreign design specifications regarding abutment wing were thoroughly examined. It has been observed that sectional forces obtained from the simplified method produce inaccurate results under various geometric shapes. Thus, it is recommended that two dimensional plate analyses should be adopted for future design of abutment wing wall.

• Journal of the Korea Institute of Military Science and Technology
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• v.1 no.1
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• pp.145-153
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• 1998

In the direct numerical optimization method, the aerodynamic coefficients of the airfoil designed by one-point design can be deteriorated at other operating points. Therefore, the capacity of the multi-point design is indispensable for actual airfoil design. In this paper, the two-point design of transonic airfoils is studied based on the Navier-Stokes equations flow solver and the feasible direction optimization algorithm, and the effects of weighting parameter were analyzed and compared. The results show that the airfoils designed by two-point design satisfy the performances at the peripheral regions of two operating points concurrently and have the favorable aerodynamic characteristics at the point which has larger weighting parameter than the other point.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.4
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• pp.289-296
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• 2011

In this study, fairing configurations for an aircraft are designed and the aerodynamic analyses of the fairings are performed to find the best choice for the aircraft. Fairings considered are wing-tip fairing and wing-body fairing. Wing alone analyses are done for the wing-tip faring selection, while wing-body-tail analyses are done for the wing-body fairing selection. A 3-D RANS solver with Menter's ${\kappa}-{\omega}$ SST turbulence model are used for the aerodynamic analyses. The effects on the drag of the aircraft are examined by comparing the analysis results with and without the farings.

• The Journal of the Acoustical Society of Korea
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• v.12 no.6
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• pp.28-35
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• 1993

팬소음은 설계변수들과 관계가 있으므로 본 논문은 실험적 방버벵 의하여 팬소음과 설계변수의 관계를 고찰하였다. 설계변수는 팬소음에 특히 영향이 큰 날개수, 날개각도, 날개끝 간극을 선택하였으며 새로운 설계변수로서 동익과 정익간의 간극과 흡입구 길이를 고찰하였다. 본 논문은 팬소음에 대한 관련된 이론을 정리하였으며 축류형 팬의 고효율 저소음 설계를 위한 방안을 제시하였다. 흡입구 길이, 날개끝 간극, 동익과 정익간의 간극등의 설계변소를 변경하여 실험한 결과 이들 설계변수들의 조정에 m이하여 축류형 팬의 고효율 저소음화를 이룰 수 있었다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.6
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• pp.471-478
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• 2018

Static tests of the composite wing structure were performed to verify damage tolerance design. Both 5 cases of DLLT and 3 cases of DULT were completed to meet requirements for static strength. After inducing BVID and open hole damages on the critical areas of the composite wing based on associated regulations, the DULT and fracture test were performed. In major wing parts, the measured strains and displacements agreed well with those of structural analysis. The initial structural fracture occurred at the area having minimum margin of safety as expected by analysis. As a result, it was confirmed that results from analytic model and strength evaluation were similar to behaviors of the composite wing structure.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1998.10a
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• pp.39-39
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• 1998

본 연구는 500KW급 수평축 풍력발전기용으로 개발된 회전날개의 시제품 제작에 앞서 축소모델에 대한, 이론적으로 예측된 공력성능과 신축에 의한 공력성능을 비교 검토함으로서, 설계결과를 검증하고, 필요한 경우 설계를 보완하여 개발위험도를 최소화하기 위해 수행되었다. 시험모델의 크기는 실제의 5%로서 직경이 2.1m이며 날개의 시위길이는 0.2r/R에서 0.101m, 날개끝에서 0.043m 이고, 날개단면형 상온 FX-S-03-182이다. 블레이드의 재질은 Glass/Epoxy 복합재료로 제작되었으며, 실제 풍황을 모사하기 위해 자연풍 상태에서 실험하였다. 실험장치의 구성은 15m 높이의 타워에 회전날개와 전자브레이크 및 각종 센서를 장착하였고, 날개가 회전하기 시작하면 제동장치에 의해 부하를 주면서 토크, 회전수, 풍속 등을 각각의 센서로부터 자료획득장치를 통해 자료처리를 할 수 있도록 하였다. 실험하는 동안 풍속은 4m/s-13m/s 정도로서 시동 풍속인 4m/s와 정격풍속인 12m/s를 포함하여 회전날개의 전체적인 특성을 파악하기 용이하였고, 이론적인 예측성능과 측정된 성능을 비교 검토한 결과 비슷한 결과를 얻어 공력설계 및 해석 방법을 검증하였다.