http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
회전익 항공기 구조건전성 향상을 위한 주륜착륙장치 결함 개선연구
장민욱(Min-Uk Jang),이윤우(Yoon-Woo Lee),서영진(Young-Jin Seo),지상용(Sang-Yong Ji) 한국산학기술학회 2019 한국산학기술학회논문지 Vol.20 No.10
착륙장치는 회전익 항공기 및 탑승 병력의 생명을 보호해야 하는 고도의 안전성이 요구되는 주요 구성품으로 이/착륙 시 충격을 흡수하고 지상에서 활주 및 계류 시 동체를 지지한다. 특히 항공기 동체를 지지하는 주륜 착륙장치는 지면으로부터 시작되는 충격을 완충장치와 타이어를 통해 대부분 흡수하는 역할을 수행하게 되는데, 이를 통해 항공기에 탑승한 조종사의 안전을 보장하고, 임무 수행 간 병력의 작전 운용능력을 만족시킨다. A 기종 회전익 항공기 운용 중에, 우측 주륜 착륙장치 구성품인 피스톤 핀(Piston Pin)이 다수 파손된 것이 확인되었다. 따라서 본 연구에서는 주륜 착륙장치에서 발견된 피스톤 핀(Piston Pin) 균열 현상에 대한 근본적인 원인을 찾기 위해, 파면 분석에서부터 비행 시험을 통한 착륙 하중 해석에 이르기까지 다양한 원인 규명 방법을 모색하였다. 특히 개발 당시 피스톤 핀에 적용되었던 드래그 빔(Drag beam) 구성품과의 체결 토크에 대한 영향성을 토대로 균열 발생 가능성들에 대한 분석을 수행하였으며, 이를 통해 피로 수명과 구조건전성을 확보할 수 있는 방안을 제시하였다. The landing gear is a component that requires a high degree of safety to protect the lives of rotary-wing aircraft and boarding personnel, absorbing the impact on transfer/landing and supporting the fuselage during taxiing and mooring on the ground. In particular, the wheel landing gear supporting the aircraft fuselage absorbs most of the shock from the ground through the shock absorber and tires. This ensures the safety of the pilot on board the aircraft and satisfies the operational capability of the soldiers between missions. During the operation of a rotary-wing aircraft, a number of piston pins, which are a component of the right main wheel landing gear, were found to be broken. Therefore, this study examined the root cause of the piston pin crack phenomenon found in the main wheel landing gear. For this purpose, various causes were identified from fracture surface analysis of a flight test. In particular, the possibility of cracking was analyzed based on the influence on the fastening torque with the drag beam component applied to the piston pin at the time of development. This ensures the fatigue life and structural integrity.
장민욱(Min-Uk Jang),명노신(Rho-Shin Myong),장인모(In-Mo Jang),이동호(Dong-Ho Lee) 한국항공우주학회 2014 韓國航空宇宙學會誌 Vol.42 No.11
효율적인 RCS 감소 연구를 위해 고주파수 근사 기법을 연계한 혼합기법 기반의 RCS 예측 코드를 개발하였다. 연계기법으로 전자기파 산란에 관한 고주파 기법인 물리광학법(Physical Optics)과 기하광학법(Geometrical Optics)을 이용하였다. RCS 산란 메커니즘의 하나인 Cavity Return 효과를 확인하기 위해 Inlet 영역은 기하광학법을 적용하였고, 그 외 영역은 물리광학법을 적용하였다. 예측코드의 정확성을 검증하기 위하여 구의 이론해와 예측결과를 비교하였고, Cavity가 존재하는 Sphere에 대한 Full Wave 해석해와 결과값을 비교하였다. 마지막으로 비행체 형상에 대한 RCS 해석문제에 적용하여 개발 코드의 유용성을 확인하였다. A hybrid method based on high-frequency asymptotic optics was developed in order to predict the RCS of flying vehicles for RCS reduction studies. In cavity return, the rays are assumed to bounce from the inlet cavity based on the laws of geometrical optics and to exit the cavity via the aperture. In other parts of a flying vehicle, the physical optics method is applied to compute the back-scattered field from the solid surface. The hybrid method was validated by considering simple models of sphere and sphere with cavity. In addition, RCS analysis of a flying vehicle was conducted using the new hybrid electromagnetic scattering method based on physical optics and geometrical optics theories.
( Kyu Min Lee ),( Sun Mi Jang ),( Seo Young Oh ),( Do Young Kim ),( Geewon Lee ),( Ahrong Kim ),( Min Ji Kim ),( Tae Hwa Kim ),( Joon Woo Park ),( Kwangha Lee ),( Ki Uk Kim ),( Min Ki Lee ),( Jung Seo 대한결핵 및 호흡기학회 2015 Tuberculosis and Respiratory Diseases Vol.78 No.4
We presented a case of unusual endobronchial inflammatory polyps as a complication following endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) in a patient with tuberculous lymphadenitis. EBUSTBNA of the right hilar lymph node was performed in a 29-year-old, previously healthy man. The patient was confirmed with tuberculous lymphadenitis and received antituberculosis medication over the course of 6 months. Chest computed tomography, after 6 months of antituberculosis therapy following the EBUS-TBNA showed nodular bronchial wall thickening of the right main bronchus. Histological and microbiological examinations revealed inflammatory polyps. After 7 months, the inflammatory polyps regressed almost completely without need for removal.
Lee, Kyu Min,Jang, Sun Mi,Oh, Seo Young,Kim, Do Young,Lee, Geewon,Kim, Ahrong,Kim, Min Ji,Kim, Tae Hwa,Park, Joon Woo,Lee, Kwangha,Kim, Ki Uk,Lee, Min Ki,Eom, Jung Seop The Korean Academy of Tuberculosis and Respiratory 2015 Tuberculosis and Respiratory Diseases Vol.78 No.4
We presented a case of unusual endobronchial inflammatory polyps as a complication following endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) in a patient with tuberculous lymphadenitis. EBUSTBNA of the right hilar lymph node was performed in a 29-year-old, previously healthy man. The patient was confirmed with tuberculous lymphadenitis and received antituberculosis medication over the course of 6 months. Chest computed tomography, after 6 months of antituberculosis therapy following the EBUS-TBNA showed nodular bronchial wall thickening of the right main bronchus. Histological and microbiological examinations revealed inflammatory polyps. After 7 months, the inflammatory polyps regressed almost completely without need for removal.
Jang, Ji-Hoon,Kim, Juyeong,Lee, Yang-Hee,Kim, In Young,Park, Min-Ho,Yang, Cheol-Woong,Hwang, Seong-Ju,Kwon, Young-Uk Royal Society of Chemistry 2011 ENERGY AND ENVIRONMENTAL SCIENCE Vol.4 No.12
<P>2–3 nm sized Pt<SUB>3</SUB>Co nanoparticles (NPs) with Pt-enriched shells on a carbon support were prepared by a one-step ultrasound polyol process on Pt(acac)<SUB>2</SUB> (acac = acetylacetonate) and Co(acac)<SUB>2</SUB>. The ultrasound facilitates the conversion of Co(acac)<SUB>2</SUB> and retards the conversion of Pt(acac)<SUB>2</SUB> into NPs, which can be explained with the different vapour pressures of the metal precursors. The Pt-enriched shell structure of the NPs by this method, as opposed to the alloy-like elemental distribution of the NPs synthesized in similar conditions but without ultrasound, was evidenced by transmission electron microscopy, magnetism data, extended X-ray absorption fine structure analyses, and chemical replacement tests of Co with Ru<SUP>3+</SUP>. Electrochemical oxygen reduction reaction data of these NPs showed improved performance from the commercial Pt/C with the NPs with Pt-enriched shells showing the highest activity.</P> <P>Graphic Abstract</P><P>Pt-rich shell/Co-rich core Pt<SUB>3</SUB>Co NPs synthesized by ultrasound indicate highly enhanced electrocatalytic activity for ORR. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c1ee01825f'> </P>