• Title/Summary/Keyword: 에어로 시스템

Search Result 305, Processing Time 0.027 seconds

Position Control of Dual Redundant Asymmetric Tandem Electro-Hydrostatic Actuator for Aircraft based on Backstepping Technique (백스테핑 기법을 이용한 항공기용 이중화 비대칭형 직렬 전기-정유압 구동기의 위치제어)

  • Kim, Daeyeon;Park, Hyung Jun;Kim, Sang Seok;Kim, Dae Hyun;Kim, Sang Beom;Lee, Junwon;Choi, Jong Yoon
    • Journal of Aerospace System Engineering
    • /
    • v.15 no.3
    • /
    • pp.1-10
    • /
    • 2021
  • The electro-hydrostatic actuators (EHA) are widely used in various industrial fields since they can independently execute the function of the hydraulic power source and have high efficiency. Particularly, in the aviation field, the EHA is mainly designed as dual redundant asymmetric tandem actuator to mitigate failure and minimize installation space. However, aviation EHAs designed in the form of dual redundant asymmetric tandem actuator have the disadvantage of decreased durability performance due to the occurrence of force fighting. In this paper, the controller is designed based on backstepping technique to improve control performance and reduce force fighting for aviation EHA. The augmented state observer is proposed to estimate the states required for control. Through simulation, it was verified that the proposed controller had superior control performance and significantly reduces the force fighting compared to the general PI controller.

Unsteady Aerodynamic Characteristics of an Non-Synchronous Heaving and Pitching Airfoil Part 1 : Frequency Ratio (비동기 히브 및 피치 운동에 따른 에어포일 비정상 공력 특성 Part 1 : 진동 주파수 비)

  • Seunghwan Ji;Cheoulheui Han
    • Journal of Aerospace System Engineering
    • /
    • v.17 no.6
    • /
    • pp.54-62
    • /
    • 2023
  • Flapping-wing air vehicles, well known for their free vertical take-off and excellent flight capability, are currently under intensive development and research. While most of the studies have explored the effect of various parameters of synchronized motions on the unsteady aerodynamics of flapping wings, limited attention has been given to the effect of nonsynchronous motions on the unsteady aerodynamic characteristics of flapping wings. In the present study, we conducted a numerical analysis to investigate the unsteady aerodynamic characteristics of an airfoil flapping with different frequency ratios between pitch and heave oscillations. We identified the motions and angle of attacks due to nonsynchronous motions. It was found that the synchronous motion produced thrust with zero lift, but the nonsynchronous motion generated a large lift with little drag. The aerodynamic characteristics of the airfoil undergoing the non-synchronous motion were also analyzed using the vorticity distributions and the pressure coefficient around and on the airfoil. When r was equal to 0.5, larger leading and trailing edge vortices were observed compared to the case when r was equal to 1.0, and these vortices significantly affected the aerodynamic characteristics of the airfoil undergoing the nonsynchronous motion. In future, the effect of pitch amplitude on the unsteady aerodynamic characteristics of the airfoil will be studied.

Synchronization of Network Interfaces in System Area Networks (시스템 에어리어 네트?에서의 동기화 기법)

  • Song, Hyo-Jung
    • Journal of KIISE:Computer Systems and Theory
    • /
    • v.32 no.5
    • /
    • pp.219-231
    • /
    • 2005
  • Many applications in cluster computing require QoS (Quality of Service) services. Since performance predictability is essential to provide QoS service, underlying systems must provide predictable performance guarantees. One way to ensure such guarantees from network subsystems is to generate global schedules from applications'network requests and to execute the local portion of the schedules at each network interface. To ensure accurate execution of the schedules, it is essential that a global time base must be maintained by local clocks at each network interface. The task of providing a single time base is called a synchronization problem and this paper addresses the problem for system area networks. To solve the synchronization problem, FM-QoS (1) proposed a simple synchronization mechanism called FBS(Feedback-Based Synchronization) which uses built-in How control signals. This paper extends the basic notion of FM-QoS to a theoretical framework and generalizes it: 1) to identify a set of built-in network flow control signals for synchrony and to formalize it as a synchronizing schedule, and 2) to analyze the synchronization precision of FBS in terms of flow control parameters. Based on generalization, two application classes are studied for a single switch network and a multiple switch network. For each class, a synchroniring schedule is proposed and its bounded skew is analyzed. Unlike FM-QoS, the synchronizing schedule is proven to minimize the bounded skew value for a single switch network. To understand the analysis results in practical networks, skew values are obtained with flow control parameters of Myrinet-1280/SAN. We observed that the maximum bounded skew of FBS is 9.2 Usec or less over all our experiments. Based on this result, we came to a conclusion that FBS was a feasible synchronization mechanism in system area networks.

The Development of Performance Test Equipment For Evaluating Endothermic Performance of Fuel Supply and Cooling System in High-Speed Vehicles (고속비행체 연료 공급 및 냉각 계통의 흡열성능 평가를 위한 성능시험 장치 개발)

  • Kim, Minsang;Choi, Won;Jun, Pilsun;Park, Jeongbae
    • Journal of Aerospace System Engineering
    • /
    • v.13 no.4
    • /
    • pp.43-49
    • /
    • 2019
  • In this study, a test equipment which enables to feed endothermic fuel which is heated in the inside and outside environment of a high-speed vehicle and evaluate the heat exchangers' performance was designed and manufactured. For smooth operation of the test equipment, a test procedure that supplied endothermic fuel at high temperatures was established. The catalyst performance test was conducted based on the supply condition of the endothermic fuel and the amount of heat absorbed was analyzed. The validation of the test equipment was proved by comparing the results of catalytic reaction with the previous studies under similar reaction condition. This test equipment can be utilized in the endothermic reaction tests of catalyzed endothermic fuel under various conditions.

The study on performance evaluation of heat resistance and smoke control system using air-curtain system in tunnel (터널용 에어커튼 시스템의 내열 및 제연 성능 평가 연구)

  • Park, Byoung-Jik;Shin, Hyun-Jun;Yoo, Yong-Ho;Park, Jin-Ouk;Kim, Yang-Kyun;Kim, Hwi-Seong
    • Journal of Korean Tunnelling and Underground Space Association
    • /
    • v.20 no.4
    • /
    • pp.743-755
    • /
    • 2018
  • Tunnel is a semi-closed structure similar to underground space where the smoke generated from fire fills the space fast while escaping from the space slow. Because of such characteristics, when the fire breaks out by traffic accident, the vehicles are jammed making it difficult for the people to evacuate from the scene as well as for the fire engine to gain access to the scene. For such reasons, tunnels are globally categorized into some disaster classes for differentiated facilities and operation approaches. In Korea, less than a 1 km-long tunnel accounts for 80.0% and such a short tunnel which is categorized into Class III is not required to have smoke control system. In this study, a full-scale fire test was conducted in a bid to apply air curtain system using heat-resistant sirocco fan to a less than 1 km-long tunnel. To that end, heat resistance test to verify the normal operation at $250^{\circ}C$ for 60 minutes was conducted. Consequently, despite of rapid rising-temperature and increasing-carbon dioxide inside the air curtain (direction of fire in tunnel), initial condition was found to have been sustained outside the air curtain (opposite direction of fire in tunnel).

A Study on the Autonomous Powered Ram Air Parafoil System Considering Wind Effect (바람 효과를 고려한 동력 램에어 파라포일 자동비행 시스템 연구)

  • Kim, Tae-Wook;Song, Yongkyu;Jeong, Dongho;Gwon, Oseong
    • Journal of the Korean Society for Aviation and Aeronautics
    • /
    • v.24 no.1
    • /
    • pp.55-61
    • /
    • 2016
  • In this work a guidance and control system for an a powered ram air parafoil under wind disturbance is considered. After analyzing a 6 Dof and 9 Dof nonlinear dynamic models of the parafoil, wind effect is added to them. In order to actively respond to the wind acting on the transverse direction of the vehicle a new guidance algorithm is proposed. After a Hardware-In-the-Loop Simulation (HILS) study, flight tests are performed to demonstrate its potential under wind disturbances.

실내공기오염관리

  • 김윤신
    • Environmental engineer
    • /
    • s.62
    • /
    • pp.12-16
    • /
    • 1991
  • 일반적으로 실내오염 제거를 위해서는 공기와 오염원을 분리시켜야 하고, 건물내의 오염원제거, 공기중의 오염원 제거, 오염물질에 대한 노출 등을 최소화시키는 것이다. 쾌적한 실내공기질을 유지하기 위하여는 건물내의 기후조건, 사용목적 등에 따라 최적의 에어클리닝 시스템을 선정하여야 한다.

  • PDF

MODIS-estimated Microphysical Properties of Clouds Developed in the Presence of Biomass Burning Aerosols (MODIS 관측자료를 이용한 러시아 산불 영향 하에 발달한 구름의 미세 물리적 특성 연구)

  • Kim, Shin-Young;Sohn, Byung-Ju
    • Korean Journal of Remote Sensing
    • /
    • v.24 no.4
    • /
    • pp.289-298
    • /
    • 2008
  • An algorithm was developed to retrieve both cloud optical thickness and effective particle radius considered the aerosol effect on clouds. This study apply the algorithm of Nakajima and Nakajima (1995) that is used to retrieve cloud optical thickness and effective particle radius from visible, near infrared satellite spectral measurements. To retrieve cloud properties, Look-up table (LUT) was made under different atmospheric conditions by using a radiative transfer model. Especially the vertical distribution of aerosol is based on a tropospheric aerosol profile in radiative transfer model. In the case study, we selected the extensive forest fire occurred in Russia in May 2003. The aerosol released from this fire may be transported to Korea. Cloud properties obtained from these distinct atmospheric situations are analysed in terms of their possible changes due to the interactions of the clouds with the aerosol particle plumes. Cloud properties over the East sea at this time was retrieved using new algorithm. The algorithm is applied to measurements from the MODerate Resolution Imaging Spectrometer (MODIS) onboard the Terra spacecrafts. As a result, cloud effective particle radius was decreased and cloud optical thickness was increased during aerosol event. Specially, cloud effective particle radius is hardly greater than $20{\mu}m$ when aerosol particles were present over the East Sea. Clouds developing in the aerosol event tend to have more numerous but smaller droplets.