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헬리콥터 진동 하중 저감을 위한 능동 뒷전 플랩이 장착된 SNUF 블레이드의 유연보의 설계 및 해석
임병욱(Byeong-Uk Im),은원종(Won-Jong Eun),신상준(SangJoon Shin) 한국항공우주학회 2018 韓國航空宇宙學會誌 Vol.46 No.7
본 논문에서는 헬리콥터의 전진비행시 발생하는 허브 진동 하중 저감을 위해 설계된 능동 뒷전 플랩이 장착된 SNUF 블레이드의 무베어링 주 로터 적용 설계에 대해 살펴보았다. 이를 위해 EDISON의 박벽 복합재료 회전보 진동해석 프로그램(CORBA77_MEMB)을 이용하여 유연보의 단면 설계가 이루어졌다. 다물체 동역학 해석 프로그램 DYMORE를 이용하여 단면 설계에 따른 블레이드 동특성 및 능동 뒷전 플랩을 이용한 하중 제어의 특성을 예측하였다. This paper presents design of a bearingless main rotor of SNUF (Seoul National University Flap) blade equipped with active trailing-edge flap to reduce the hub vibratory loads during helicopter forward flight. For that purpose, sectional design of the flexbeam is carried out using the thin-walled composite material rotating beam vibration analysis program (CORBA77_MEMB) in EDISON. Using the multi-body dynamics analysis program, DYMORE, blade dynamic characteristics and those of the loads control are examined using the active trailing-edge flap in terms of the flexbeam sectional design.
임재욱 ( Jae Uk Im ),김은혜 ( Eun Hye Kim ),전홍길 ( Hong Gil Jun ),오지선 ( Ji Seon Oh ),최승원 ( Seung Won Choi ),강병성 ( Byeong Seong Kang ) 대한내과학회 2013 대한내과학회지 Vol.84 No.6
The gastrointestinal tract is commonly involved in patients with systemic sclerosis. The manifestations include motility disorder, pseudo-obstruction, malabsorption, bacterial overgrowth, diverticuli, and, less commonly, pneumatosis cystoides intestinalis (PCI). PCI is characterized by the presence of air in the submucosal or subserosal layer of the bowel wall and is often accompanied by pneumoperitoneum. Although PCI is a benign condition that often responds to conservative management, it is a poor prognostic factor of systemic sclerosis. We report a case of PCI in a patient with systemic sclerosis. The chest and abdominal radiographic findings comprised pneumoperitoneum, marked dilation of the bowels, and intramural air, compatible with PCI. The patient`s symptoms improved spontaneously. It is important to recognize PCI as a gastrointestinal manifestation of systemic sclerosis, and physicians should differentiate it from serious complications-such as intestinal perforation-based on clinical manifestations. (Korean J Med 2013;84:868-872)
MODEL BASED OPTIMUM PID GAIN DESIGN OF ADAPTIVE FRONT LIGHTING SYSTEM
Shin Hyun Park,Byeong Uk Im,Dong Kyou Park 한국자동차공학회 2018 International journal of automotive technology Vol.19 No.5
Adaptive Front-Lighting System (AFLS) is a system which assists driver's field of vision by automatically controlling its brightness and illumination angle to adapt various driving conditions such as climate, traffic, road changes and so forth. This paper aims to propose novel model-based PID gain design method to improve the performances of Dynamic Bending Light (DBL) module that change horizontal angle of a system by applying Brent-Dekker algorithm that finds the root of nonlinear function and implementing Nelder-Mead simplex algorithm to the system reduction process. Along with the linear system model-based control theory, motor dynamics were modeled with frequency response. Validation of the prototype resulted in having less than 3 % error from the simulation, where position initialization and the real-time status monitoring function is available due to the closed loop control which enables over 3 times faster response than the conventional open-loop system.
큐브위성 임무를 위한 테이프 스프링 힌지의 비선형 거동 분석 및 실험
유정욱(JeongUk Yoo),임병욱(Byeong-Uk Im),신상준(SangJoon Shin) 한국항공우주학회 2019 韓國航空宇宙學會誌 Vol.47 No.10
본 연구에서는 최근 다양한 큐브위성 임무에 사용되는 테이프 스프링 힌지의 거동 해석을 수행하였다. 테이프 스프링은 곡선 단면을 갖는 직선형의 얇은 스트립이며 곡률에 따라 달라지는 강성변화로 인해 비선형성이 강하게 발생한다. 이전 연구에서 제시된 회전-모멘트 선도 모델을 바탕으로 테이프 스프링의 거동 특성을 분석하였으며, 시중에 판매되는 상용 테이프 스프링 형상을 정확하게 모사하여 ABAQUS 수치 해석을 진행하였다. 테이프 스프링을 굽히는데 소요되는 최대 모멘트를 예측하였으며 단면의 원호각이나 두께 등의 변화에 따른 파라미터 스터디를 수행하였다. 또한 간략한 실험을 통해 수치해석 결과를 비교 검증하여 보다 정밀한 큐브위성 동적 거동 해석을 위한 향후 연구 방향을 제시한다. This paper explores an implementation of finite element analysis and experiment in the design process of a tape spring hinge used for various CubeSat missions. Tape spring hinges consist of short-length hardened-steel strips with one-sided curvature, and thus the behavior is subject to large deformation with unpredicted non-linearity. Precise dimensions of a commercial tape spring are traced by the use of high-resolution digital camera, and thin-shell FEM analysis is conducted using ABAQUS program. Based on the rotation-moment analysis suggested in previous studies, parametric analysis is conducted by adjusting the contributing factors such as strip thickness and the subtended angle of the cross section. Finally the behaviors are investigated by both analytical and non-linear finite element methods, and the results are compared with the simple measurements. Further studies suggest a possible application in dynamic characteristics of hinges during CubeSat operations.