• Title/Summary/Keyword: Rigid Object

Search Result 146, Processing Time 0.029 seconds

제공전투기의 초음속 순항 성능 향상을 위한 가변 앞전형상 에어포일의 개념설계 제안

  • Yun, Yeong-Jun
    • Proceeding of EDISON Challenge
    • /
    • 2016.03a
    • /
    • pp.647-652
    • /
    • 2016
  • To reduce drag force at supersonic speeds, sharp leading edge is hugely efficient. It is, however, incompatible with leading edge shape to have fine aerodynamic characteristics at subsonic and transonic speeds. It is critical to reduce drag force for enhanced cruise performance and higher efficiency. An air superiority fighter, however, required to have high maneuverability for survivability, and sharp leading edge is not proper. Consequently, variable leading edge is demanded to reduce drag force significantly at supersonic speeds for cruise performance. Leading edge altering system is constructed with rigid material to improve possibility of realization, and minimized movement of its components in altering for reduce effects on flight. It is compared with bi-convex airfoil and NACA 65-006 airfoil, which have comparable maximum thickness. At Mach number 1.7 and zero angle of attack, supersonic mode of designed airfoil indicates approximately 17% higher drag coefficient than the bi-convex airfoil indicates, it is, however, 23% lower than the NACA 65-006 indicates. Also, subsonic mode of the designed airfoil shows fine aerodynamic characteristics in comparison with NACA 65-006 airfoil in subsonic and transonic speed range. In this regard, design of the airfoil achieved the object of this study satisfactorily.

  • PDF

VIRTUAL PASSIVITY-BASED DECENTRALIZED CONTROL OF MULTIPLE 3-WHEELED MOBILE ROBOTIC SYSTEMS VIA SYSTEM AUGMENTATION

  • SUH J. H.;LEE K. S.
    • International Journal of Automotive Technology
    • /
    • v.6 no.5
    • /
    • pp.545-554
    • /
    • 2005
  • Passive velocity field control (PVFC) was previously developed for fully mechanical systems, in which the motion task was specified by behaviors in terms of a velocity field and the closed-loop was passive with respect to the supply rate given by the environment input. However, the PVFC was only applied to a single manipulator. The proposed control law was derived geometrically and the geometric and robustness properties of the closed-loop system were also analyzed. In this paper, we propose a virtual passivity-based algorithm to apply decentralized control to multiple 3­wheeled mobile robotic systems whose subsystems are under nonholonomic constraints and convey a common rigid object in a horizontal plain. Moreover, it is shown that multiple robot systems ensure stability and the velocities of augmented systems converge to a scaled multiple of each desired velocity field for cooperative mobile robot systems. Finally, the application of proposed virtual passivity-based decentralized algorithm via system augmentation is applied to trace a circle and the simulation results is presented in order to show effectiveness for the decentralized control algorithm proposed in this research.

Geometry Cutting Solution using Vector Dot Product (벡터 내적연산을 이용한 지오메트리 절삭 솔루션)

  • Hwang, Min Sik
    • Journal of Korea Multimedia Society
    • /
    • v.19 no.8
    • /
    • pp.1337-1344
    • /
    • 2016
  • As the visual effect frequently used in movies or animations, special effects are well suited for the creation of buildings or materials' destruction and collapse scenes. With the relevant programs developing technologically, the adoption of a real-time physically based-system makes it possible to realistically express dynamic simulations. In the large scale, the visual expression of such effects of destroying is satisfying enough, but most common programs of those effects fail to maximize visual effect generated with the cutting of small materials. Besides, to perform a heavy simulation process needs high-performance hardware and programs, where high costs would become a serious issue. For this reason, this paper suggests a solution optimized for the effect of small materials-cutting. The progress of each step shows technologies which trace movement with the state of the completion of the character's motions and then cut the material in real-time, finally led to the very realistic visual effect. Besides, using vector inner calculation to follow the motions of object and to realize cutting effect, this study provides an experiment that constructs visual effect for visualization from the basis of mathematical algorithm and it would be certainly as an educational material used for further researches.

Friction Welding Analysis of Welding Part Shape with Flow Gallery Considered Fluid Flow (유체 유동을 고려한 유동부를 갖는 용접부 형상의 마찰용접 해석)

  • Yeom, Sung-Ho;Kim, Bum-Nyun;Hong, Sung-In
    • Journal of the Korean Society of Propulsion Engineers
    • /
    • v.11 no.3
    • /
    • pp.7-12
    • /
    • 2007
  • Friction welding is a welding method to use frictional heat of a couple of materials. In this paper object is that design the welding part shape with the flow gallery part which there is no effect in flow. Decided the welding part design parameter and doing the friction welding analysis used the rigid-plastic FEM program DEFORM-2D. To do friction welding analysis must input necessary flow stress data, friction coefficient by temperature change, upset pressure and Revolution per minute etc. According to analysis result, it decided the optimal shape of welding part with no effect in flow.

Development of a Dynamic Simulation Program for Railway Vehicles (철도차량을 위한 동역학 해석 프로그램 개발)

  • Cho, Jae-Ik;Park, Tae-Won;Yoon, Ji-Won;Kim, Young-Guk
    • Proceedings of the KSR Conference
    • /
    • 2009.05b
    • /
    • pp.473-479
    • /
    • 2009
  • Dynamic analysis is necessary for the High-Speed Railway vehicle which aims to run on max 400km/h. Especially, dynamic simulation using CAE(Computer Aided Engineering) can help to reduce the time of development of the High-Speed Railway vehicles. Also, it helps to reduce prices and improve the quality such as safety, stability and ride. There are many dynamic software for a railway vehicle, such as Vampire and ADAMS-Rail. There are limitations for each software and difficulties to analyze overall dynamics for entire railway system. To overcome these limitations, in this study, a program which can simulate entire railway vehicles was developed. This program is easy to use because it was developed using C++, which is object-oriented programming language. In addition, the basic platform for the development of dynamic solver is prepared using the nodal, modal coordinate system with a wheel-rail contact module. Rigid, flexible and large deformable body systems can be modeled by a user according to the characteristic of a desired system. Its reliability is verified by comparison with a commercial analysis program.

  • PDF

Re-reading the film of Dead Poets Society (영화<죽은 시인의 사회> 다시 읽기)

  • Yang, Hyun-Mi
    • English & American cultural studies
    • /
    • v.9 no.1
    • /
    • pp.297-321
    • /
    • 2009
  • The purpose of this study is to re-read the film of Dead Poets Society, specially focused on a feminist view. The film hides the strategy of recovering the traditional Patriarchal Society. At the beginning, the film resists the values of traditional society through John Keating. His unorthodox methods of teaching literature smack against the traditions of Welton Academy. Furthermore, he stresses on "Carpe Diem"—Seize the Day, the romantic values of free thinking, creativity, and individuality. The forces opposing Keating's philosophy are personified by Welton's rigid, old headmaster, Mr. Nolan, and the cruel, stubborn parent, Mr. Perry. Keating's romantic values are failed by their powerful, dominating attitudes. Effected by Keating's philosophy, Neil decides to pursue acting rather than medicine. He conflicts with his strict father. Finally frustrated by his authority, Neil commits suicide. And Keating is accused of inciting the boys to restart the Dead Poets Society, and at last he is fired. Keating and Neil are victimized by the Patriarchal society. Even though the film concentrates male characters at the all boys' school, it reveals the male angle of binary oppositions between men and women, subject and object, activity and passivity, presence and absence. In the film's dramatic conclusion, English class is now being temporarily taught by Nolan, who has the boys read from the very Pritchard essay they had ripped out at the start of the film. It symbolizes the triumph of the traditional logocentric society. However, influenced by Keating's unconventional attitudes, ultimately Welton Academy will be changed as it is embodied in its closing scene.

Recent Advances in Soft Magnetic Actuators and Sensors using Magnetic Particles (자성 분말 기반 소프트 자성 액츄에이터 및 센서 연구 동향)

  • Song, Hyeonseo;Lee, Hajun;Kim, Junghyo;Kim, Jiyun
    • Journal of Powder Materials
    • /
    • v.28 no.6
    • /
    • pp.509-517
    • /
    • 2021
  • Smart materials capable of changing their characteristics in response to stimuli such as light, heat, pH, and electric and magnetic fields are promising for application to flexible electronics, soft robotics, and biomedicine. Compared with conventional rigid materials, these materials are typically composed of soft materials that improve the biocompatibility and allow for large and dynamic deformations in response to external environmental stimuli. Among them, smart magnetic materials are attracting immense attention owing to their fast response, remote actuation, and wide penetration range under various conditions. In this review, we report the material design and fabrication of smart magnetic materials. Furthermore, we focus on recent advances in their typical applications, namely, soft magnetic actuators, sensors for self-assembly, object manipulation, shape transformation, multimodal robot actuation, and tactile sensing.

Removal of a Bronchial Foreign Body by Bronchoscopic Cryotherapy: A Case Study

  • Kim, Hyoyeon;Byun, Gwanghyun;Lee, Sang Joon;Woo, Seung Hoon
    • Medical Lasers
    • /
    • v.10 no.1
    • /
    • pp.55-59
    • /
    • 2021
  • A foreign body in the airway can be a potentially life-threatening event. The diagnosis and treatment of foreign bodies in the airway are a challenge for otolaryngologists. Despite the improvements in medical care and public awareness, approximately 3,000 deaths occur each year from foreign body aspiration. A high degree of vigilance is required to ensure prompt treatment and avoid the complications of foreign body aspiration. The author encountered a case of a 77-year-old female patient who had aspirated an unknown foreign body that was fixed in her main bronchus. An initial attempt was made to remove it with a flexible bronchoscope but failed due to the patient's hypoxemic state during the procedure. Under general anesthesia, a rigid bronchoscopic examination was performed, but it was difficult to approach the object due to the bronchus curvature. Instead, a cryotherapy instrument of bronchoscopy was applied. The foreign body was frozen and removed to the carina, where a laryngoscope and laryngeal forceps were used to remove it.

Foreign body aspirations in dental clinics: a narrative review

  • Huh, Jin-Young
    • Journal of Dental Anesthesia and Pain Medicine
    • /
    • v.22 no.3
    • /
    • pp.161-174
    • /
    • 2022
  • Foreign body aspiration can produce a medical emergency. Obstruction of the airways can be life-threatening, and complications may develop in less-severe cases if it is left untreated. Although it is more prevalent in children by approximately three times, adults can still experience it, and it is more frequently related to healthcare in adults. Objects used in dental treatment are usually placed in the oral cavity and can be ingested or inhaled by accident. Dental treatment has been identified as an important cause of the misplacement of foreign bodies in the airway. However, few reports have been published on dentistry-related foreign body aspiration. This paper discusses the disease course, management, and clinical outcomes of foreign body aspiration, especially those associated with dentistry. The patient must be examined for respiratory distress. If the patient is unstable, urgent airway management and the maneuvers for removal should be performed. Radiographs and computed tomography can help identify and locate the object. The treatment of choice is often bronchoscopy, and both flexible and rigid endoscopes can be used depending on the situation. Preventive measures need to be implemented to avoid inhalation accidents given the potential consequences. Though the incidence is rare, healthcare levels need to be enhanced to avert morbidity and mortality. Radiological evaluation and bronchoscopy are vital for management.

Rotating Brush Strokes to Track Movement for Painterly Rendering (회학적 렌더링에서 움직임을 따라 회전하는 붓질 기법)

  • Han, Jeong-Hun;Gi, Hyeon-U;Kim, Hyo-Won;O, Gyeong-Su
    • 한국HCI학회:학술대회논문집
    • /
    • 2008.02a
    • /
    • pp.426-432
    • /
    • 2008
  • We introduce a method of rendering a scene lying 3D objects which is like that artist draw on a canvas by brushing. Painting is the art area presenting something created by color and line on 2D plane. We are brushing on billboards on screen space for the 2D brushing effect according to the definition of "Painting". Brushing orientation is haven to rotate for preventing the orientation in the first scene in the case that object or camera are moving. If the brushing isn't rotated, shower-door effect is watched on the scene as undesirable result We present a brushing rotating method for keeping the orientation changing the direction of view and object rigid animation. The brushing direction is computed with Horn's 2D similarity transform by least-square solution. We watched the changing brushing to track the motion of object and view.

  • PDF