• 한국항행학회논문지
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• 제11권1호
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• pp.43-49
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• 2007

본 논문에서는 Rummler 모델 기반의 케이블 채널에서 OFDM/64QAM 시스템의 성능을 시뮬레이션을 수행하여 평가하고, 적응 LMS 등화기를 적용하여 성능 개선 정도를 평가하였다. 성능 평가 결과, Rummler Two-ray 채널에서 반사파에 대한 감쇠계수(b)가 0.15 이하인 경우에는 등화기를 채용하여야 성능 개선 정도가 크게 이루어짐을 알 수 있었다. 그리고 b가 0.15이상인 경우에는 등화기를 채용해도 Eb/No에 관계없이 거의 동일한 성능이 얻어짐을 알 수 있었다.

• 한국항공운항학회지
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• 제18권3호
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• pp.55-69
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• 2010

The role of airports in the metropolitan area in Korea is very important which is located on the center of Northeast Asia considered as the highest potential growth continent in the world air transport market. This study includes comparison on service quality between Gimpo Airport and Incheon Airport which are indicated as multi-airport system in the metropolitan area appraised by passengers from Korea, Japan and China, and analysis on primary factors of airport service which affect the customer satisfaction and loyalty. The service quality appraised in the order of Chinese, Korean, and Japanese and the analysis result indicated that the service quality factors which influence on customer satisfaction and loyalty were all different among passengers from three countries. Information service was the priority factor for customer satisfaction to Chinese and Korean, but Japanese considered that personal service was the most important factor. This research paper tried to provide many current issues and guides to operational strategy including plan for the specialized routes of multi-airport system in domestic metropolitan area.

• Journal of Mechanical Science and Technology
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• 제17권9호
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• pp.1358-1370
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• 2003

The effects of anode, cathode, and cooling channels for a Proton Exchange Membrane Fuel Cell (PEMFC) on flow fields have been investigated numerically. Continuous open-faced fluid flow channels formed in the surface of the bipolar plates traverse the central area of the plate surface in a plurality of passes such as a serpentine manner. The pressure distributions and velocity profiles of the hydrogen, air and water channels on bipolar plates of the PEMFC are analyzed using a two-dimensional simulation. The conservation equations of mass, momentum, and energy in the three-dimensional flow solver are modified to include electro-chemical characteristics of the fuel cell. In our three-dimensional numerical simulations, the operation of electro-chemical in Membrane Electrolyte Assembly (MEA) is assumed to be steady-state, involving multi-species. Supplied gases are consumed by chemical reaction. The distributions of oxygen and hydrogen concentration with constant humidity are calculated. The concentration of hydrogen is the highest at the center region of the active area, while the concentration of oxygen is the highest at the inlet region. The flow and thermal profiles are evaluated to determine the flow patterns of gas supplied and cooling plates for an optimal fuel cell stack design.

• 한국항행학회논문지
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• 제9권2호
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• pp.156-163
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• 2005

본 논문에서는 ICAO (International Civil Aviation Organization)에서 규정한 VDL 모드 3 시스템 계통도와 제원을 구성하여 BER(Bit Error Rate), 전송지연시간, 버스트 재전송율, 그리고 throughput에 대한 성능을 분석하였다. 성능 분석 결과, BER과 전송지연시간, throughput, 버스트 재전송율의 관계를 명확히 정의할 수 있었고, 또한 down link에서 V/D 재전송율과 throughput에 강한 상관이 있음이 판명되었다.

• 한국항공운항학회지
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• 제22권3호
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• pp.24-32
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• 2014

Due to the rapid growth of domestic and overseas airline markets, the demand for airline pilots has also been growing fast. Meeting such a market needs, central government, Ministry of Land and Transportation has set up civil airline pilot training center at Ulgin airport to train and provide the market with commercial airline pilots. Not only central government but universities in Korea also have tried to train pilots by operating flight training academies. Even though there are more than a dozen of flight training centers including colleges and private academies, there have been less efforts to measure and evaluate the effectiveness of the flight training school's curriculums compared to other scholar majors in a university. Therefore this paper tried to evaluate the educational effectiveness of the curriculums using the Kirk-Patrick measurement model, which has been regarded as one of the most popular and accurate measurement tool for an empirical research in social science. According to the empirical research, it was found out the inter-personal relationship between an instructor pilot and flight trainee was perceived as the most important factor to have an impact on learning abilities and student's behaviors.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권12호
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• pp.6243-6259
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• 2019

As a foundation of next-generation air transportation systems, automatic dependent surveillance-broadcast (ADS-B) helps pilots and air traffic controllers create a safer and more efficient national airspace system. Owing to the open communication environment, it is easy to insert fake aircraft into the system via spoofing or the insertion of false messages. Efforts have thus been made in academic research and practice in the aviation industry to ensure the security of transmission of messages of the ADS-B system. An identity-based batch verification (IBV) scheme was recently proposed to enhance the security and efficiency of the ADS-B system, but current IBV schemes are often too resource intensive because of the application of complex hash-to-point operations or bilinear pairing operations. In this paper, we propose a lightweight IBV signature scheme for the ADS-B system that is robust against adaptive chosen message attacks in the random oracle model, and ensures the security of batch message verification and against the replaying attack. The proposed IBV scheme needs only a small and constant number of point multiplication and point addition computations instead of hash-to-point or pairing operations. Detailed performance analyses were conducted to show that the proposed IBV scheme has clear advantages over prevalent schemes in terms of computational cost and transmission overhead.

• Journal of Mechanical Science and Technology
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• 제17권8호
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• pp.1234-1245
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• 2003

An experimental study was carried out to investigate the reduced frequency effect on the near-wake of an elliptic airfoil oscillating in pitch. The airfoil was sinusoidally pitched around the center of the chord between -5$^{\circ}$and ＋25$^{\circ}$angles of attack at an airspeed of 3.4 m/s. The chord Reynolds number and reduced frequencies were 3.3 ${\times}$10$^4$, and 0.1, 0.7, respectively Phase-averaged axial velocity and turbulent intensity profiles are presented to show the reduced frequency effects on the near-wake behind the airfoil oscillating In pitch. Axial velocity defects in the near-wake region have a tendency to increase in response to a reduced frequency during pitch up motion, whereas it tends to decrease during pitch down motion at a positive angle of attack. Turbulent intensity at positive angles of attack during the pitch up motion decreased in response to a reduced frequency, whereas turbulent intensity during the pitch down motion varies considerably with downstream stations. Although the true instantaneous angle of attack compensated for a phase-lag is large, the wake thickness of an oscillating airfoil is not always large because of laminar or turbulent separation.

• 한국항공운항학회지
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• 제30권1호
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• pp.44-49
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• 2022

This study performed precision instrument landing procedures for pilots with a commercial pilot license using VR HMD flight simulators, and assuming that the center of the pilot's gaze is in the front, 3-D.O.F. head tracking data and 2-D eye tracking of VR HMD worn by pilots gaze tracking was performed through. After that, AOI (Area of Interesting) was set for the instrument panel and external field of view of the cockpit to analyze how the pilot's gaze was distributed before and after the decision altitude. At the same time, the landing results were analyzed using the Localizer and G/S data as the pilot's precision instrument landing flight data. As a result, the pilot was quantitatively evaluated by reflecting the gaze tracking and the resulting landing result using a VR HMD simulator.

• 항공우주의학회지
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• 제31권3호
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• pp.64-67
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• 2021

When the COVID-19 crisis hit air transport, the whole aviation industry was affected. The change in the behavior of passengers following the COVID-19 crisis, travel restrictions and the ensuing economic crisis have resulted in a dramatic drop in demand for airline services. The COVID-19 pandemic, with all its associated consequences, has had a significant impact on the mental health and well-being of pilots, which could impact operational safety. As the number of international flights has decreased, pilots are exposed to high levels of psychological stress such as job instability, reduced income and increased risk of infection during flight work. Psychological stress lowers work performance and threatens aviation safety. The pilot needs mental health management during the COVID-19 pandemic, but psychological support is weak. For pilot mental health management, it is important to raise awareness about mental health and to continuously respond. To this end, it is necessary to foster a safe and trustworthy culture in which mental health issues are discussed freely and solved together without hiding them. They should also support the establishment of a peer support program that is easily accessible and that allows pilots to discuss their issues with confidence.

• 한국항공운항학회지
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• 제30권4호
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• pp.159-168
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• 2022

본 연구의 목적은 공항 세금 환급시스템의 혁신적 특성과 중국인 탑승객의 개인 통제신념이 수용 의도에 미치는 영향을 규명하고자 하였다. 본 연구는 계획된 행동이 세금환급을 받으려는 의도에 미치는 영향에 대해 이론적으로 고찰하고 분석하였다. 공항에서 세금환급시스템을 이용한 경험이 있는 중국인 탑승객 343명을 대상으로 자료를 수집하였다. 실증 분석 결과, 시스템 혁신적 특성에서 상대적 이점, 적합성 및 복잡성이 높고, 인식된 위험이 낮을수록, 개인 통제신념에서 행동신념, 규범신념 및 통제신념이 높을수록 이용자의 수용의도가 높은 것으로 판명되었다. 이용자 채택 단계에 따른 수용 의도 간의 차이를 분석한 결과, 초기 수용자 집단이 후기 수용자 집단보다 수용 의도가 높은 것으로 나타났다. 이용자의 채택 단계에 따라 수용 의도에 영향을 미치는 요인은 차이가 있었는데, 초기 수용자 집단에서는 시스템 혁신적 특성 중 적합성과 개인 통제신념이 중요한 변수였으며, 후기 수용자 집단에서는 시스템 혁신 특성 중 인식된 위험과 규범신념을 제외한 개인의 통제신념이 중요한 변수로 분석되었다. 따라서 공항 세금 환급시스템에 대한 초기 수용자들에게는 더 많은 확신을 줄 필요가 있으며, 후기 수용자들에게는 지각된 위험을 감소시켜 주어야 할 것이다.