• Title/Summary/Keyword: Collision In The Air

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A Study on the Improvement of Aviation Safety in Jeju Southern Air Corridor(AKARA-FUKUE Corridor) (제주남단 항공회랑(AKARA-FUKUE Corridor)의 항공안전 개선에 관한 연구)

  • Ahn, Hee-Bok;Hwang, Ho-Won
    • Journal of the Korean Society for Aviation and Aeronautics
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    • v.29 no.2
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    • pp.55-66
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    • 2021
  • ICAO recommended that airspace monitoring and periodic safety assessments in each Contracting State ensure the stability of the airspace, since reducing the aircraft lateral and vertical separation intervals would rather increase the risk of collision. The target level of safety of the AKARA-FUKUE Corridor at the southern end of Jeju was 247×10-9. In simple comparison, this means that the risk of an aircraft collision in this area (international safety standards, 5.0×10-9) is about 50 times higher. The scope of this study is to organize the concept of terms, analyze the air traffic volume, the current status of navigational safety facility usage fees, and investigations of an aircraft collision risk in Jeju southern air corridor. Analyzing government policies and overseas evaluations, revising some of the existing contents, presenting some of the additional contents of new routes, and changing the instrument procedure for Korean-Chinese routes, change of arrive/departure route between Incheon Airport and Shanghai Airport, reduce the risk of aircraft collisions. We hope to restore airspace sovereignty, contribute to policies for the government to take the lead in solving this problem, and expect stability and operational efficiency in air traffic.

Collision Efficiency Estimation in the DAF Contact Zone using Computational Fluid Dynamics (전산유체 기법을 이용한 용존공기부상법에서의 접촉도 조건변화에 따른 충돌효율평가)

  • Kim, Sung-Hoon;Yoo, Je-Seon;Park, Hee-Kyung
    • Journal of Korean Society of Water and Wastewater
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    • v.18 no.2
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    • pp.201-207
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    • 2004
  • Dissolved air flotation (DAF) is a solid-liquid separation process that uses fine rising bubbles to remove particles in water. Most of particle-bubble collision occurs in the DAF contact zone. This initial contact considered by the researchers to play a important role for DAF performance. It is hard to make up conceptual model through simple mass balance for estimating collision efficiency in the contact zone because coupled behavior of the solid-liquid-gas phase in DAF system is 90 complicate. In this study, 2-phase(gas-liquid) flow equations for the conservation of mass, momentum and turbulence quantities were solved using an Eulerian-Eulerian approach based on the assumption that very small particle is applied in the DAF system. For the modeling of turbulent 2-phase flow in the reactor, the standard $k-{\varepsilon}$ mode I(liquid phase) and zero-equation(gas phase) were used in CFD code because it is widely accepted and the coefficients for the model are well established. Particle-bubble collision efficiency was calculated using predicted turbulent energy dissipation rate and gas volume fraction. As the result of this study, the authors concluded that bubble size and recycle ratio play important role for flow pattern change in the reactor. Predicted collision efficiency using CFD showed good agreement with measured removal efficiency in the contact zone. Also, simulation results indicated that collision efficiency at 15% recycle ratio is higher than that of 10% and showed increasing tendency of the collision efficiency according to the decrease of the bubble size.

Comparative Evaluation on Collision and Particle Separation Efficiency between CO2 Bubbles and Air Bubbles Using Contact Zone Model of Flotation Process (부상분리 공정의 접촉영역 모델을 이용한 이산화탄소와 공기 기포의 충돌 및 입자 분리효율 비교 평가)

  • Yang, Jong-Won;Choi, Yong-Ho;Chae, In-Seok;Kim, Mi-Sug;Jeong, Yong-Hoon;Kim, Tae-Geum;Kwak, Dong-Heui
    • Journal of Korean Society on Water Environment
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    • v.35 no.1
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    • pp.64-71
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    • 2019
  • In recent years, carbon dioxide ($CO_2$) bubbles emerged as the most widely applied material with the recycling of sequestrated storage to decrease global warming. Flotation using $CO_2$ as an alternative to air could be effective in overcoming the high power consumption in the dissolved air flotation (DAF) process. The comparison of DAF and DCF system indicated that, the carbon dioxide flotation (DCF) system with pressurized $CO_2$ only requires 1.5 ~ 2.0 atm, while the DAF system requires 3.0 ~ 6.0 atm. In a bid to understand the characteristics of particle separation, the single collector collision (SCC) model was used and a series of simulations were conducted to compare the differences of collision and flotation between $CO_2$ bubbles and air bubbles. In addition, laboratory experiments were sequentially done to verify the simulation results of the SCC model. Based on the simulation results, surfactant injection, which is known to decrease bubble size, cloud improved the collision efficiency of $CO_2$ bubbles similar to that of air bubbles. Furthermore, the results of the flotation experiments showed similar results with the simulation of the SCC model under anionic surfactant injection. The findings led us to conclude that $CO_2$ bubbles can be an alternative to air bubbles and a promising material as a collector to separate particles in the water and wastewater.

A Study on the collision avoidance system between aircraft and drones due to the activation of the drone industry (드론 산업 활성화에 따른 항공기와 드론 간 공중 충돌 회피 시스템에 관한 고찰)

  • Kim, Sa-Woong
    • The Journal of the Korea institute of electronic communication sciences
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    • v.16 no.5
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    • pp.969-974
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    • 2021
  • South Korea is making efforts to select a drone industry, a type of unmanned aerial vehicle, as one of the 7 major industries in the country, to select a drone-specific liberalization zone and to establish and revise a drone-related bill. Through these efforts, drone delivery and drone taxis are expected to be operated in the future. Therefore, a multilateral collision avoidance system with existing aircraft such as drones, fixed-wing and rotary-wing should be established to prepare for possible drone and air-borne collisions.

Collision Tree Based Anti-collision Algorithm in RFID System (RFID시스템에서 충돌 트리 기반 충돌방지 알고리즘)

  • Seo, Hyun-Gon
    • Journal of KIISE:Information Networking
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    • v.34 no.5
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    • pp.316-327
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    • 2007
  • RFID (Radio Frequency Identification) is one of the most promising air interface technologies in the future for object identification using radio wave. If there are multiple tags within the range of the RFID tag reader, all tags send their tag identifications to the reader at the same time in response to the reader's query. This causes collisions on the reader and no tag is identified. A multi-tag identification problem is a core issue in the RFID. It can be solved by anti-collision algorithm such as slot based ALHOA algorithms and tree based algorithms. This paper, proposes a collision tree based anti-collision algorithm using collision tree in RFID system. It is a memory-less algorithm and is an efficient RFID anti-collision mechanism. The collision tree is a mechanism that can solve multi-tag identification problem. It is created in the process of querying and responding between the reader and tags. If the reader broadcasts K bits of prefix to multiple tags, all tags with the identifications matching the prefix transmit the reader the identifications consisted of k+1 bit to last. According to the simulation result, a proposed collision tree based anti-collision algorithm shows a better performance compared to tree working algorithm and query tree algorithm.

Collision Avoidance Maneuver of Unmanned Aerial Vehicles Applying TCAS-II (TCAS-II를 응용한 무인항공기의 충돌회피기동 연구)

  • Jo, Sin-Je;Kim, Jong-Seong;Jang, Dae-Su;Tak, Min-Je;Gu, Hwon-Jun
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.34 no.4
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    • pp.33-39
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    • 2006
  • In this paper, the collision avoidance of Unmanned Aerial Vehicles(UAVs) by applying the Traffic alert and Collision Avoidance System II(TCAS-II) is introduced. The performances of two UAVs whose maximum vertical rates are different each other are compared and analysed by not only converting many TCAS-II commands into an autopilot input but also implementing a computer program based on the Minimum Operational Performance Standards for TCAS-II. As the alternative to a possible Near Mid-Air Collision for UAVs whose maximum vertical rates are low, we have proposed a modified algorithm considering the maximum vertical rate and altitude. The modified algorithm is available on the assumption that a wider surveillance range is provided by a ADS-B system.

Improvement of the Avoidance Performance of TCAS-II by Employing Kalman Filter (Kalman Filter를 적용한 TCAS-II 충돌회피 성능 개선)

  • Jun, Byung-Kyu;Lim, Sang-Seok
    • Journal of Advanced Navigation Technology
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    • v.15 no.6
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    • pp.986-993
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    • 2011
  • In this paper we consider the problem of the existing TCAS-II systems that fail to be satisfactory solution to mid-air collisions (MACs) and near mid-air collisions (NMACs or near misses). This is attributed to the fact that the earlier studies on the collision avoidance mainly have focused on determination logic of avoidance direction and vertical speed, reversal of the avoidance direction, multiple aircraft geometry, and availability in certain air spaces. But, the influence of sensor measurement errors on the performance of collision avoidance was not properly taken into account. Here we propose a new TCAS algorithm by using Kalman filter instead of '${\alpha}-{\beta}$' tracker to improve the avoidance performance under the influence of barometric sensor errors due to air-temperature, pressure leaks, static source error correction, etc.

Design of small impact test device for concrete panels subject to high speed collision

  • Kim, Sanghee;Jeong, Seung Yong;Kang, Thomas H.K.
    • Advances in concrete construction
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    • v.7 no.1
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    • pp.23-30
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    • 2019
  • Five key items were used to create an economical and physically small impact test device for concrete panels subject to high speed collision: an air-compressive system, carbon steel pipe, solenoid valve, carrier and carrier-blocking, and velocity measurement device. The impact test device developed can launch a 20 mm steel spherical projectile at over 200 m/s with measured impact and/or residual velocity. Purpose for development was to conduct preliminary materials tests, prior to large-scale collision experiments. In this paper, the design process of the small impact test device was discussed in detail.

Effect of Bubble Size in DAF (DAF에서 기포크기의 영향)

  • Park, Yong-Hyo;Han, Moo-Young
    • Journal of Korean Society of Water and Wastewater
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    • v.17 no.4
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    • pp.528-533
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    • 2003
  • Bubble size is one of the most important parameters affecting DAF (Dissolved-Air-Flotation) process. It is generally known that small bubbles are preferred. However, the fact seems to be based on the particle removal efficiency at contact zone only, without considering separation zone. Besides, the effect of bubble size on the overall DAF process has not been fully investigated yet. Therefore, the effect of bubble size on collision efficiency, collision chances, and surface loading rate is calculated using theoretical models, and the results are discussed in this paper.

A Study on the Design of Alert System for Preventing Collision Accidents (소형선학의 충돌사고예방을 위한 경보시스템 설계)

  • Lee Eun Bang
    • Proceedings of KOSOMES biannual meeting
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    • 2003.11a
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    • pp.105-108
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    • 2003
  • A ultrasonic alert system is proposed in order to prevent the collision accidents of srmll ships. This system displays a lamp and a sound signal alerting collision by trrmsmitting ultrasonic pulse in air to detect ships and objects within fXJ m Under the condition of restricted visibility and compliazted works, it is expected to enh:uu:e the effect if navigators' lookout.

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