• Title/Summary/Keyword: Aviation Turbulence

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A Review on the Implementation of TAPS: Airlines Application Plan and Expected Effectiveness (항공사의 TAPS 활용 방안과 기대효과 고찰)

  • Bae, In-Seok;Kim, Hyo-Jung
    • 한국항공운항학회:학술대회논문집
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    • 2015.11a
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    • pp.102-106
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    • 2015
  • 항공 운송량의 증가로 운항 중 예상치 못한 난류(Turbulence)에 직면하는 경우도 증가하고 있다. 이로 인한, 손님/승무원의 부상, 화물 손상, 항공기 효율성 하락 등으로 많은 Cost가 발생하고 있으며, 항공 안전에도 치명적인 위협이 되고 있다. 하지만, 이에 대한 정보는 운항 중인 항공기의 조종사기상보고(Pilot Weather Reports, PIREP)에 의존하여 발생 지역을 예측하고 있으나, 보고시간 지체에 따른 부정확한 위치, 주관적인 강도 예측으로 실제 유사 지역을 운항하는 항공기에 도움을 주는데 한계가 있다. 금번 논문에서 TAPS(Turbulence Auto PIREP System)의 원리와 실제 운영하는 항공사의 활용 방안을 고찰하여, 정보의 자동 송/수신을 통한 실시간 난류 정보 제공으로 위험 요인을 사전 인지하여 제거할 수 있는 방안을 살펴보고자 한다.

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A Study on the Air Travel Safety of Infants and Children (영유아 항공 여행 안전성에 관한 고찰)

  • Kim, Sun Ah;Choi, Youn Seo;Kim, Sun Ihee
    • Journal of the Korean Society for Aviation and Aeronautics
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    • v.26 no.3
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    • pp.93-104
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    • 2018
  • It is mandatory to use car seats for infants and children in the private vehicles in accordance with the traffic law of Korea. Recently, legislation has also been proposed to expand the use car seats to express and intercity buses. This reflects a growing consensus that mandatory infant and child car seats, both for private and commercial vehicles, are essential. However, Korean laws concerning infants and children on board aircraft allow parents or guardians to hold children under two years of age on their laps without any restraint devices. It is not possible for a parent to physically restrain an infant or child, especially during a sudden acceleration or deceleration, unanticipated or severe turbulence, or impact. The use of CRS provides an equivalent level of safety to infants and children as that afforded to adult passengers wearing seat belts. But there is no regulation even about Child Restraint Systems on board aircraft in Korea. To enhance their safety, infants and children should be restrained in an approved child restraint system that is appropriate to their weight and height. It is necessary to examine whether infants and children in flight can achieve the same level of safety as an adult.

Characterization of the internal flow and fuel spray from an impinging flow nozzle (노즐분공내 유체충돌이 있는 디젤노즐의 유동 및 분무특성 연구)

  • Ha, Seong-Eop;Kim, Heung-Yeol;Gu, Ja-Ye;Ryu, Gu-Yeong
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.21 no.12
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    • pp.1635-1646
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    • 1997
  • The nozzle length to diameter ratio of real diesel nozzles is about 2-8 which is not long enough for a fully developed and stabilized flow. The characteristics of the flow such as turbulence at the nozzle exit which affect the development of the spray can be enhanced by impinging the flow inside nozzle. The flow details inside the impinging nozzles have been investigated both experimentally and numerically. The mean velocities, the fluctuating velocities, and discharge coefficients in the impinging inlet nozzles, round inlet nozzle, and sharp inlet nozzle were obtained at various Reynolds number. The developing feature of the external spray were photographed by still camera and the droplet sizes and velocities were also measured by laser Doppler technique. The spray angle was greater and the droplet sizes near the spray axis were smaller with the impinging flow inside nozzle.

Analysis of Low Altitude Wind Profile Data from Wind Lidar for Drone Aviation Safety (드론의 안전 비행을 위한 윈드라이다 저고도 바람 분석 방법 제시)

  • Kim, Je-Won;Ryu, Jung-Hee;Na, Seong-Jun;Seong, Seong-Cheol
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.50 no.12
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    • pp.899-907
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    • 2022
  • According to the Unmanned aircraft system Traffic Management (UTM), drones are permitted to fly up to 150m above ground, which is located in the atmospheric boundary layer where there is considerable wind fluctuation due to turbulence. Although it is difficult to predict when turbulence will occur drone aviation safety could be enhanced by having a better understanding of the characteristics of vertical profile of wind in the flight area. We used wind lidar (WIndMast 350M) to observe vertical profiles of wind at the test site for aviation meteorological observation equipment located near Incheon International Airport in July and September, 2022. In this study, we utilized the observed wind profile data to propose a technique for obtaining information that could help improve the drone aviation safety. The Fourier transform analysis is used to evaluate the temporal characteristics of the horizontal wind speed at various vertical levels up to 350m. We also examined the relative contribution of the variance of wind having scales of less than an hour, a crucial scale for drone flight, to the variance of wind having all scales at each vertical altitude for days with and without precipitation.

Aviation Convective Index for Deep Convective Area using the Global Unified Model of the Korean Meteorological Administration, Korea: Part 1. Development and Statistical Evaluation (안전한 항공기 운항을 위한 현업 전지구예보모델 기반 깊은 대류 예측 지수: Part 1. 개발 및 통계적 검증)

  • Yi-June Park;Jung-Hoon Kim
    • Atmosphere
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    • v.33 no.5
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    • pp.519-530
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    • 2023
  • Deep convection can make adverse effects on safe and efficient aviation operations by causing various weather hazards such as convectively-induced turbulence, icing, lightning, and downburst. To prevent such damage, it is necessary to accurately predict spatiotemporal distribution of deep convective area near the airport and airspace. This study developed a new index, the Aviation Convective Index (ACI), for deep convection, using the operational global Unified Model of the Korea Meteorological Administration. The ACI was computed from combination of three different variables: 3-hour maximum of Convective Available Potential Energy, averaged Outgoing Longwave Radiation, and accumulative precipitation using the fuzzy logic algorithm. In this algorithm, the individual membership function was newly developed following the cumulative distribution function for each variable in Korean Peninsula. This index was validated and optimized by using the 1-yr period of radar mosaic data. According to the Receiver Operating Characteristics curve (AUC) and True Skill Score (TSS), the yearly optimized ACI (ACIYrOpt) based on the optimal weighting coefficients for 1-yr period shows a better skill than the no optimized one (ACINoOpt) with the uniform weights. In all forecast time from 6-hour to 48-hour, the AUC and TSS value of ACIYrOpt were higher than those of ACINoOpt, showing the improvement of averaged value of AUC and TSS by 1.67% and 4.20%, respectively.

Transonic Flutter Characteristics of Supercritical Airfoils Considering Shockwave and Flow Separation Effects (충격파 및 유동박리 효과를 고려한 초임계 에어포일의 천음속 플러터 특성)

  • Lin, Han;Kim, Dong-Hyun;Kim, Yu-Sung;Kim, Yo-Han;Kim, Seok-Soo
    • Journal of the Korean Society for Aviation and Aeronautics
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    • v.17 no.2
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    • pp.8-17
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    • 2009
  • In this study, flutter analyses for supercritical airfoil have been conducted in transonic region. Advanced computational analysis system based on computational fluid dynamics (CFD) and computational structural dynamics (CSD) has been developed in order to investigate detailed static and dynamic responses of supercritical airfoil. Reynolds-averaged Navier-Stokes equations with Spalart-Allmaras (S-A) and SST ${\kappa}-{\omega}$ turbulence models are solved for unsteady flow problems. A fully implicit time marching scheme based on the Newmark direct integration method is used for computing the coupled aeroelastic governing equations of cascades for fluid-structure interaction (FSI) problems. Also, flow-induced vibration (FIV) analyses for various supercritical airfoil models have been conducted. Detailed flutter responses for supercritical are presented to show the physical performance and vibration characteristics in various angle of attack.

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Aviation Convective Index for Deep Convective Area using the Global Unified Model of the Korean Meteorological Administration, Korea: Part 2. Seasonal Optimization and Case Studies (안전한 항공기 운항을 위한 현업 전지구예보모델 기반 깊은 대류 예측 지수: Part 2. 계절별 최적화 및 사례 분석)

  • Yi-June Park;Jung-Hoon Kim
    • Atmosphere
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    • v.33 no.5
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    • pp.531-548
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    • 2023
  • We developed the Aviation Convective Index (ACI) for predicting deep convective area using the operational global Numerical Weather Prediction model of the Korea Meteorological Administration. Seasonally optimized ACI (ACISnOpt) was developed to consider seasonal variabilities on deep convections in Korea. Yearly optimized ACI (ACIYrOpt) in Part 1 showed that seasonally averaged values of Area Under the ROC Curve (AUC) and True Skill Statistics (TSS) were decreased by 0.420% and 5.797%, respectively, due to the significant degradation in winter season. In Part 2, we developed new membership function (MF) and weight combination of input variables in the ACI algorithm, which were optimized in each season. Finally, the seasonally optimized ACI (ACISnOpt) showed better performance skills with the significant improvements in AUC and TSS by 0.983% and 25.641% respectively, compared with those from the ACIYrOpt. To confirm the improvements in new algorithm, we also conducted two case studies in winter and spring with observed Convectively-Induced Turbulence (CIT) events from the aircraft data. In these cases, the ACISnOpt predicted a better spatial distribution and intensity of deep convection. Enhancements in the forecast fields from the ACIYrOpt to ACISnOpt in the selected cases explained well the changes in overall performance skills of the probability of detection for both "yes" and "no" occurrences of deep convection during 1-yr period of the data. These results imply that the ACI forecast should be optimized seasonally to take into account the variabilities in the background conditions for deep convections in Korea.

Numerical study on the oblique shock wave/vortex interaction (경사충격파와 와류 상호작용에 대한 수치적 연구)

  • Mun, Seong-Mok;Kim, Jong-Am;No, O-Hyeon
    • 한국항공운항학회:학술대회논문집
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    • 2004.11a
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    • pp.240-246
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    • 2004
  • For the prediction on the onset of oblique shock wave-induced vortex breakdown, computational studies on the Oblique Shock wave/Vortex Interaction (OSVI) are conducted and compared with both experimental results and analytic model. A Shock-stable numerical scheme, the Roe scheme with Mach number-based function (RoeM), and a two-equation eddy viscosity-transport approach are used for three-dimensional turbulent flow computations. The computational configuration is identical to available experiment, and we attempt to ascertain the effect of parameters such as a vertex strength, streamwise velocity deficit, and shock strength at a freestream Mach number of 2.49. Numerical simulations using the ${\kappa}-{\omega}SST$ turbulence model and suitably modeled vortex profiles are able to accurately reproduce many fine features through a direct comparison with experimental observations. The present computational approach to determine the criterion on the onset of oblique shock wave-induced vortex breakdown is found to be in good agreement with both the experimental result and the analytic prediction.

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Control of the flow past a sphere in a turbulent boundary layer using O-ring

  • Okbaz, Abdulkerim;Ozgoren, Muammer;Canpolat, Cetin;Sahin, Besir;Akilli, Huseyin
    • Wind and Structures
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    • v.35 no.1
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    • pp.1-20
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    • 2022
  • This research work presents an experimental study's outcomes to reveal the impact of an O-ring on the flow control over a sphere placed in a turbulent boundary layer. The investigation is performed quantitatively and qualitatively using particle image velocimetry (PIV) and dye visualization. The sphere model having a diamater of 42.5 mm is located in a turbulent boundary layer flow over a smooth plate for gap ratios of 0≤G/D≤1.5 at Reynolds number of 5 × 103. Flow characteristics, including patterns of instantaneous vorticity, streaklines, time-averaged streamlines, velocity vectors, velocity fluctuations, Reynolds stress correlations, and turbulence kinetic energy (), are compared and discussed for a naked sphere and spheres having O-rings. The boundary layer velocity gradient and proximity of the sphere to the flat plate profoundly influence the flow dynamics. At proximity ratios of G/D=0.1 and 0.25, a wall jet is formed between lower side of the sphere and flat plate, and velocity fluctuations increase in regions close to the wall. At G/D=0.25, the jet flow also induces local flow separations on the flat plate. At higher proximity ratios, the velocity gradient of the boundary layer causes asymmetries in the mean flow characteristics and turbulence values in the wake region. It is observed that the O-ring with various placement angles (𝜃) on the sphere has a considerable alteration in the flow structure and turbulence statistics on the wake. At lower placement angles, where the O-ring is closer to the forward stagnation point of the sphere, the flow control performance of the O-ring is limited; however, its impact on the flow separation becomes pronounced as it is moved away from the forward stagnation point. At G/D=1.50 for O-ring diameters of 4.7 (2 mm) and 7 (3 mm) percent of the sphere diameter, the -ring exhibits remarkable flow control at 𝜃=50° and 𝜃=55° before laminar flow separation occurrence on the sphere surface, respectively. This conclusion is yielded from narrowed wakes and reductions in turbulence statistics compared to the naked sphere model. The O-ring with a diameter of 3 mm and placement angle of 50° exhibits the most effective flow control. It decreases, in sequence, streamwise velocity fluctuations and length of wake recovery region by 45% and 40%, respectively, which can be evaluated as source of decrement in drag force.

Negligence theory of Aviation accident with reference to the japanese aviation accident precedent (항공 사고에서의 과실 이론 - 일본 항공 사고 판례를 중심으로 -)

  • Hwang, Ho-Won;Ham, Se-Hun
    • The Korean Journal of Air & Space Law and Policy
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    • v.23 no.2
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    • pp.115-136
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    • 2008
  • The development of the aviation technology is beyond the people's imagination. For example, with some exaggeration, If the autopilot engage upon take off, You will realize that you are on the centerline of the foggy JFK runway 13R after 15 hours with only once or twice of intervention. But the more aviation technology develops, the more responsible the pilot will be who has the final authority of the aviation safety. In the JAL 706 accident caused by unidentified reason, the pilot increased pitch abruptly and overrode the control from the autopilot. The result of this process made the death of a flight attendant and some injuries of a few passengers. The district court found the pilot not guilty at the first trial on the ground that the control override was not connected to the possibility of foresight and avoidance of the human death. The pilot was proved to be innocent through the analysis of the DFDR and ADAS that the override did not precede the unidentified pitch up motion. The judicial precedent related to aviation accidents in Korea requires pilots' absolute and extended care compared to the ordinarily prudent or reasonably careful behaviors in the vehicle and medical accidents. Although there is some controversy about the standard care, the care required in the actual operation of high tech aircraft by a pilot should include objective and standard care and be judged by analysis of the scientific data. Although the pilot maintained the unusual hi speed that doesn't have safety margin and descended under turbulence in case of the JAL 706 accident, the court negatived its relation to the cause of pitch up. Also, the override of the control after initial pitch up might have caused the possibility of the death and injury, but the court denied it. Because of this complex cause of the aviation accidents, it is important for a court to figure out the core reason of the event and casual relationship with the pilot Now, It is required that the judgement of negligence in the aviation accidents should include an objective care with scientific data from simulated circumstances(or a simulator) as the Japanese court not from the theory of vehicle's negligence.

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