• Journal of Communications and Networks
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• 제16권4호
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• pp.447-457
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• 2014

In this paper, we investigate the frequency domain channel estimation for multiple-input multiple-output (MIMO) single-carrier frequency-division multiple-access (SC-FDMA) systems. In MIMO SC-FDMA, code-division multiplexed (CDM) pilots such as cyclic-shifted Zadoff-Chu sequences have been adopted for channel estimation. However, most frequency domain channel estimation schemes were developed based on frequency-division multiplexing of pilots. We first develop a channel estimation error model by using CDM pilots, and then analyze the mean-square error (MSE) of various minimum MSE (MMSE) frequency domain channel estimation techniques. We show that the cascaded one-dimensional robust MMSE (C1D-RMMSE) technique is complexity-efficient, but it suffers from performance degradation due to the channel correlation mismatch when compared to the two-dimensional MMSE (2D-MMSE) technique. To improve the performance of C1D-RMMSE, we design a robust iterative channel estimation (RITCE) with a frequency replacement (FR) algorithm. After deriving the MSE of iterative channel estimation, we optimize the FR algorithm in terms of the MSE. Then, a low-complexity adaptation method is proposed for practical MIMO SC-FDMA systems, wherein FR is performed according to the reliability of the data estimates. Simulation results show that the proposed RITCE technique effectively improves the performance of C1D-RMMSE, thus providing a better performance-complexity tradeoff than 2D-MMSE.

• 한국의류산업학회지
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• 제22권6호
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• pp.844-852
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• 2020

This study is to understand the preferences of pilots, flight engineers and crew who work in the same aircraft but are exposed to different working environments and perform different mission operations in order to develop an ergonomic flight jacket. Based on a preliminary investigation, a survey of 107 pilots and 36 flight engineers and crew was conducted. The results are as follows; Pilots can control the temperature inside the cockpit, so they are less exposed to the cold when working, while flight engineers and crew are exposed to the cold more because they have many external tasks. The reason for the problem of the current flight jacket was a difference in ranking between two groups, but the highest ranking was poor dimensional suitability due to the habit of wearing layers of clothing. As a result of preferred design, there were significant differences between groups in the item of overall style. Pilots preferred a bomber jacket style(P:68.2%, E&C:44.4%), on the other hand, flight engineers and crew preferred a field jacket style(P:26.2%, E&C:55.6%)(p<.01). They preferred a stand collar(P:71.0%, E&C:86.1%), a fastener slider for a front fastening(P:62.6%, E&C:61.1%), fastener tape cuffs(P:54.2%, E&C:47.2%), a jacket with a softshell(P:86.9%, E&C:83.3%), fleece as softshell material(P:88.8%, E&C:69.4%), and fastener sliders as a attaching method(P:69.2%, E&C:61.1%). A hem fastening will be selected differently according to the overall style of outshell. Additionally, they preferred more than 5ea pockets(P:51.4%, E&C:44.4%), fastener sliders as pocket's fastenings(P:48.6%, E&C:61.1%), armpit ventilations(P:62.9%, E&C:58.5%). The results of above will be considered to design an ergonomic flight jacket.

• 한국항행학회논문지
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• 제28권1호
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• pp.44-50
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• 2024

본 연구는 국내 민간 항공사 조종사 193명을 대상으로 비행 스트레스가 직무 만족도 및 안전문화에 미치는 영향을 분석하였다. 분석 결과, 비행 스트레스는 직무 만족도에 부정적 영향을 미쳤으며, 직무 만족도가 낮은 조종사는 안전문화 인식도 낮게 나타났다. 특히, 항공사와 조종사의 직급에 따라 비행 스트레스가 직무 만족도와 안전문화에 미치는 영향에 차이를 보였다. 이는 항공사와 조종사 직급별로 맞춤형 스트레스 관리 프로그램 개발의 필요성을 시사한다. 연구는 항공 산업의 안전 문화 강화를 위해 조종사의 스트레스 관리와 직무 만족도 향상이 중요함을 강조한다. 또한, 항공사는 조종사의 스트레스를 감소시키고, 직무 만족도를 높여 안전문화를 강화하는 전략을 개발해야 한다. 본 연구 결과는 항공산업에서 조종사들의 스트레스 관리와 안전문화 강화를 위한 방안 모색에 유용한 기초 자료로 활용하기 위함이다.

• 한국항행학회논문지
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• 제28권1호
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• pp.60-67
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• 2024

민간항공사고의 대부분은 인적요인에 의해 발생하고 특히 회전익 항공기는 예상하지 못하거나 의도하지 않게 악기상으로 진입하는 IIMC (instrument meteorological conditions) 상황에서의 사고가 많이 발생하고 있다. 이 연구는 저시정 조건에서 회전익 항공기 조종사의 에러율를 다각적으로 분석하여 비행특성에 관한 통찰력을 얻고 IIMC 상황에서의 사고를 줄이기 위한 방안을 연구하였다. 저시정 조건에서 조종사의 에러 발생율을 모션이 장착된 비행 시뮬레이터를 활용하였으며 65명의 조종사가 실험에 참여하였다. 실험을 통해 획득한 비행 데이터로 비행시정 감소, 공간정위상실 유무, 조종사 자격 등 다양한 조건에 따라 에러 발생율을 비교 분석하였다. 분석결과 다양한 조건에서 비행특성에 대한 특이점을 발견할 수 있었고 조종사의 자격 등급, 계기비행 (IFR; instrument flight rules) 자격 유무, 비행단계별 에러 발생율에 유의미한 차이가 발생하였다. 이와 같은 연구의 결과는 조종사의 교육 및 훈련프로그램을 개선하고 IIMC 상황에서 항공기 사고예방에 중요한 기여를 할 것으로 기대된다.

• 한국항공운항학회지
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• 제26권1호
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• pp.1-9
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• 2018

Ground effect includes a reduction of induced drag, increase of lift, and nose-down moment during landing. These phenomena, occurring late in the landing maneuver, are considered to be of little significance because they tend to counteract and/or compensate in this respect. Even though it is unlikely to affect any flare profile variations appreciably, some pilots have reversed perception about such phenomenon and overestimate during landing. It is becoming a negative factor and is making an adverse effect on landing maneuver. This study examines the perception of ground effect of large aircraft pilots, reviews literature regarding ground effect, and makes suggestions that pilots can correctly recognize and respond to the effect during landing flare maneuvers.

• 한국항공운항학회지
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• 제18권2호
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• pp.41-45
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• 2010

It is often misled that Multi Pilot License is introduced by International Civil Aviation Organization for the shortage of pilots. The truth is, however, that the license is focused on efficient training of co-pilots in the airline transportation system which an autopilot system is increasing in the Multi Crew environment. ICAO has been researching on the license since 1982, and made it international standard on 2006. Currently, co-pilots trained under Multi-Crew Pilot License courses are continuously increasing over the world. Although the license has introduced to Korea in September 10, 2009, it has not won popular support yet. This paper will lead people to precise understanding of Multi-Crew Pilot License and suggest its introduction plan.

• 한국항공운항학회지
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• 제23권3호
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• pp.88-93
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• 2015

Among other various aspects of safety culture, this research has considered safety culture from the view of aviation. A tool to examine aviation safety culture has been developed on the basis of Global Aviation Safety Network's safety culture survey. Using this tool, the degree of perception of Korean national carriers' pilots in safety culture has been examined three times for the period from 2002 to 2015. Compared to an initial result of the survey in 2002, results in 2008 and 2015 demonstrate that safety culture among pilots has rapidly changed from negative and bureaucratic to positive. Hence, it is expected that positive index of safety culture will increase 28% (total approximate 90%) in 2020.

• 한국항공운항학회지
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• 제19권3호
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• pp.33-42
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• 2011

This study focused to find the main factors causing job stress to ROKAF pilots and of which factors affects to turnover intention. As a results, the factors of job stress are job characteristics, over loaded ground work, payment, promotion and employee benefits & service system. All of these 5 factors are positively related to the causes of a pilot stress. Among the job stress factors, payment, promotion and over loaded ground work are positively related as the same order. But, job characteristics and employee benefits & service system are not. Even though ROKAF pilots are stressed by annual requirement and night flying, and also are stressed by unfulfilled welfare, those two stress factors are not related to the turnover intention.

• 한국항공운항학회지
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• 제12권2호
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• pp.71-81
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• 2004

There are four methods of landing of B747-400 during the crosswind condition. Pilots can choose either one of them. Those are: Sideslip/Wing low, De-Crab during Flare, Touchdown in Crab, Combining Crab and Sideslip. They decide to use one method by what they have learnt before. During the flight, the pilots choose the method, which depends on the weather forecast, and then try to land according to it. However, the weather condition always changes. In other words, the weather during planning and landing can be different, which can provide a difference between the previously expected situation and the actual one. Therefore, it is very important for the pilots to have the situation awareness. This study shows the direction and the prevention to avoid those errors, which are based on actual landing data of B747-400.

• 대한안전경영과학회지
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• 제8권2호
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• pp.71-80
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• 2006

There are many display panels in the flight cockpit and pilots get various flight information from those displays. The ergonomic layout of the displays must be determined based upon frequency of use and sequence of use. This study investigated the visual search patterns of the six display groups(one head-up-display: HUD, two multi function displays: MFDs, one engine group: EG, one flight display group: FD and others) in a fighting aircraft. Four expert pilots conducted Imaginary flight in the physical mock-up and the eye movements were collected using eye tracking system. Data of dwell time, frequency of use, and eye movement path were collected. Pilots spent most of time on HUD(55.2%), and others (21.6%), FD(14.2%), right MFD(4.7%), EG(3.2%), and left MFD(1.1%) in descending order. Similarly HUD(42.8%) and others(30.0%) were the most frequently visited displays. These data can be used in the layout of cockpit displays and the determination of optimal visual search pattern.