• Title/Summary/Keyword: Low-altitude

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A Study on the Attitude about the Family/Kinship Life of Netizen (네티즌의 가족/친족관련 가치관과 태도)

  • 고선주
    • Journal of the Korean Home Economics Association
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    • v.40 no.5
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    • pp.159-177
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    • 2002
  • The purpose of this exploratory study was to investigate how the information society affected the attitude about the family/kinship life of Netizen. For this goal, the data were collected from 305 Netizen who use the Internet. The major findings were as follows. Firstly, In Netizen, the support to familism and boy preference was low level. Secondly, in their altitude to the divorce and remarriage, there was a tendency which accepts a marriage with selection. Thirdly, they had a tendency to agree equal partnership in couple relationship. Fourthly, virtual community in cyber-space was found, but the loyalty of members was not enough strong. Fifthly, in the family/kin rites, it was showed non-traditional tendency. And in all aspects, some differences were found between men and women. The findings of the present study suggest that the couple relationship in the information society becomes more important, and there is a tend to increase acceptability to increase. In contrast, there is stiff another discrimination in cyber-space by focusing on traditional mother route.

Three-Dimensional Computations of Rocket Exhaust Plume (로켓 배기플룸에 관한 3차원 수치해석)

  • Kim Y.-M.
    • 한국전산유체공학회:학술대회논문집
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    • 1999.11a
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    • pp.71-76
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    • 1999
  • The base flow regions of a three-body sounding rocket containing multiple exhaust plumes were numerically investigated in three dimensions for a free stream Mach number of 2.7 at flight altitude 18.5 km. The flowfields were calculated using the full compressible Navier-Stokes equations with an one-equation turbulence model of Baldwin-Earth. The present calculations were executed based upon a chemically frozen, single perfect gas model assumption. Due to the symmetry of the three-body rocket of each single nozzle, only one fourth of the computational domain was considered for the analysis. The results indicate that a babe heating effect is not considerable due to the small expansion of the plumes. In the base, however, a low speed recirculating flow dominates the region.

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Numerical Analysis of Nonequilibrium Chemically Reacting Inviscid flow over Blunt-bodies Using Upwind Method (Upwind 방법을 이용한 무딘물체 주위의 화학적 비평형 비점성 유동장의 수치 해석)

  • Seo Jeong Il;Song Dong Joo
    • 한국전산유체공학회:학술대회논문집
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    • 1997.10a
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    • pp.99-105
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    • 1997
  • A finite-difference method based on conservative supra characteristic method type upwind flux difference splitting has been developed to study the nonequilibrium chemically reacting inviscid flow. For nonequilibrium air, NS-1 species equations were strongly coupled with flowfield equations through convection and species production terms. Inviscid nonequilibrium chemically reacting air mixture flows over Blunt-body were solved to demonstrate the capability of the current method. At low altitude flight conditions the nonequilibrium air models predicted almost the same temperature, density and pressure behind the shock as equilibrium flow: however, at high altitudes they showed substantial differences due to nonequilibrium chemistry effect. The new nonequilibrium chemically reacting upwind flux difference splitting mettled can be extended to viscous flow and multi-dimensional flow conditions.

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The Design of Path Length Controller in Ring Laser Gyroscope for Attitude Control in the LEO satellite (저궤도 위성 자세제어 센서 RLG 피에조 구동기 설계)

  • Kim, Eui-Chan;Lee, Heung-Ho
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.57 no.9
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    • pp.1584-1588
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    • 2008
  • The Ring Laser Gyroscope makes use of the Sagnac effect within a resonant ring cavity of a He-Ne laser and has more accuracy than the other gyros. The Low Earth Orbit satellite for observatory use require the high accuracy Gyro to control and determine the altitude because of the need of payload pointing accuracy. In this paper, The theory of the Path Length Control is explained. The electrical design of Path Length Controller is described. The Design for Path Length Controller is composed of the demodulator, integrator, phase shifter, high voltage amplifier. We apply the circuit to 28cm square ring laser gyro and get the test results.

Obstacle Awareness and Collision Avoidance Radar Sensor System for Smart UAV

  • Kwag, Young K.;Hwang, Kwang Y.;Kang, Jung W.
    • International Journal of Aeronautical and Space Sciences
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    • v.6 no.2
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    • pp.97-109
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    • 2005
  • In this paper, the critical requirement for obstacle awareness and avoidance is assessed with the compliance of the equivalent level of safety regulation, and then the collision avoidance sensor system is presented with the key design parameters for the requirement of the smart unmanned aerial vehicle in low-altitude flight. Based on the assessment of various sensors, small-sized radar sensor is selected for the suitable candidate due to the real-time range and range-rate acquisition capability of the stationary and moving aircraft even under all-weather environments. Through the performance analysis for the system requirement, the conceptual design result of radar sensor model is proposed with the range detection probability and collision avoidance mode is established based on the time-to-collision, which is analyzed by collision scenario.

Simulation Modeling of Range and Acceleration Measurement Instruments for Satellite Formation Flying (편대비행 위성용 거리 및 가속도 관측기 시뮬레이션 모델링)

  • Kim, Jeong-Rae
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.33 no.2
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    • pp.75-83
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    • 2005
  • NASA/DLR Gravity Recovery and Climate Experiment (GRACE) mission, which consists of two co-orbiting low altitude satellites, is to measure the Earth gravity field with unprecedented accuracy. Its key instruments include inter-satellite ranging systems and three-axis accelerometers. For the preliminary design and requirements analysis, extensive instrument simulation models are developed. These modeling techniques and orbit-gravity field estimation techniques are described.

Application of UAT ADS-B (UAT ADS-B의 국내 적용방안)

  • Kim, Kyung-Ho;Choi, Sung-Ho;Baik, Ho-Jong;Lee, Keum-Jin;Moon, Woo-Chun
    • Journal of the Korean Society for Aviation and Aeronautics
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    • v.20 no.2
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    • pp.26-31
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    • 2012
  • A new operational concept for the CNS/ATM using the digital data communication technology and satellite navigation system is being implemented globally and the United States is the first country to apply UAT ADS-B system for general aviation. Korea also has plan to build ADS-B system for aeronautical surveillance to monitor low altitude flight of light aircraft and ultra-light flying device and the research to develop UAT ADS-B equipment is being carried out. This paper presents the application method of UAT ADS-B to support test operation with case study of foreign UAT ADS-B operation and survey of domestic environment.

An Approach to the Spectral Signature Analysis and Supervised Classification for Forest Damages - An Assessment of Low Altitued Airborne MSS Data -

  • Kim, Choen
    • Korean Journal of Remote Sensing
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    • v.7 no.2
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    • pp.149-163
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    • 1991
  • This paper discusses the capabilities of airborne remotely sensed data to detect and classify forest damades. In this work the AMS (Aircraft Multiband Scanner) was used to obtain digital imagery at 300m altitude for forest damage inventory in the Black Forest of Germany. MSS(Multispectral Scanner) digital numbers were converted to spectral emittance and radiance values in 8 spectral bands from the visible to the thermal infrared and submitted to a maximum-likelihood classification for : (1) tree species ; and. (2) damage classes. As expected, the resulted, the results of MSS data with high spatial resolution 0.75m$\times$0.75m enabled the detection and identification of single trees with different damages and were nearly equivalent to the truth information of ground checked data.

Ground Test of Model SCRamjet Engine with Free-Piston Shock Tunnel

  • Kang, Sang-Hun;Lee, Yang-Ji;Yang, Soo-Seok;Smart, Michael;Suraweera, Milinda
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2008.03a
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    • pp.452-455
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    • 2008
  • Model Scramjet engine is tested with T4 free-piston shock tunnel at University of Queensland, Australia. Basically, test condition is fixed as Mach 7.6 at 31 km altitude. With this condition, variation effects of fuel equivalence ratio, cavity, cowl setting and angle of attack were investigated. In the results, supersonic combustion was observed with low and middle fuel equivalence ratio. At high equivalence ratio, thermal choking was occurred due to the intensive reaction. Cavity and W-shape cowl showed early ignition and enhanced mixing respectively.

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A Study on Pedestrians Tracking using Low Altitude UAV (저고도 무인항공기를 이용한 보행자 추적에 관한 연구)

  • Seo, Chang Jin
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.67 no.4
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    • pp.227-232
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    • 2018
  • In this paper, we propose a faster object detection and tracking method using Deep Learning, UAV(unmanned aerial vehicle), Kalman filter and YOLO(You Only Look Once)v3 algorithms. The performance of the object tracking system is decided by the performance and the accuracy of object detecting and tracking algorithms. So we applied to the YOLOv3 algorithm which is the best detection algorithm now at our proposed detecting system and also used the Kalman Filter algorithm that uses a variable detection area as the tracking system. In the experiment result, we could find the proposed system is an excellent result more than a fixed area detection system.