• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.513-520
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• 2004

A steady-state/transient performance simulation model was newly developed for the propulsion system of the CRW (Canard Rotor Wing) type UAV (Unmanned Aerial Vehicle) during flight mode transition. The CRW type UAV has a new concept RPV (Remotely Piloted Vehicle) which can fly at two flight modes such as the take-off/landing and low speed forward flight mode using the rotary wing driven by engine bypass exhaust gas and the high speed forward flight mode using the stopped wing and main engine thrust. The propulsion system of the CRW type UAV consists of the main engine system and the duct system. The flight vehicle may generally select a proper type and specific engine with acceptable thrust level to meet the flight mission in the propulsion system design phase. In this study, a turbojet engine with one spool was selected by decision of the vehicle system designer, and the duct system is composed of main duct, rotor duct, master valve, rotor tip-jet nozzles, and variable area main nozzle. In order to establish the safe flight mode transition region of the propulsion system, steady-state and transient performance simulation should be needed. Using this simulation model, the optimal fuel flow schedules were obtained to keep the proper surge margin and the turbine inlet temperature limitation through steady-state and transient performance estimation. Furthermore, these analysis results will be used to the control optimization of the propulsion system, later. In the transient performance model, ICV (Inter-Component Volume) model was used. The performance analysis using the developed models was performed at various flight conditions and fuel flow schedules, and these results could set the safe flight mode transition region to satisfy the turbine inlet temperature overshoot limitation as well as the compressor surge margin. Because the engine performance simulation results without the duct system were well agreed with the engine manufacturer's data and the analysis results using a commercial program, it was confirmed that the validity of the proposed performance model was verified. However, the propulsion system performance model including the duct system will be compared with experimental measuring data, later.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2005년도 제24회 춘계학술대회논문집
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• pp.92-95
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• 2005

본 연구는 기존의 폭발볼트와는 달리 작동에 필요한 전원의 공급 없이 수행하면서, 또한 지연기능까지 포함한 비전기식 지연형 폭발볼트에 관한 것이다. 즉 비전기식 작동방법을 이용하여 전원 공급 장치를 없앨 수 있기 때문에 분리장치의 소형화가 가능해졌고, 이를 위하여 기존 폭발볼트의 작동 메카니즘과는 다른 새로운 개념의 메카니즘을 적용하였고, 또한 지연기능을 추가하기 위하여 작동메카니즘 개발과 별도로 지연장치를 개발하였다. 전원을 사용하지 않고 작동하는 착화장치를 설계하기 위하여 폭발볼트가 결합된 비행체에서 발생하는 공기의 저항력을 이용하였다. 고속으로 비행하는 발사체의 속도를 줄이고 안전한 착륙을 위한 낙하 시스템의 설계에 고려될 수 있는 장치라고 생각된다.

• 한국항공운항학회지
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• 제18권3호
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• pp.77-83
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• 2010

"The prohibition of careless or reckless flight" is the regulation specified not only in the national air law but ICAO ANNEX and FAR. This article(item) has not been categorized properly unlike other items and the question such as why this is described as a fundamental and essential act can be answered only by the party subjected to administrative measures in case of Korea and this kind of violation is so rare that it is not easy to understand the legal meaning and the function of the term, "The prohibition of careless or reckless flight" In case of U.S where aviation cases are common, the distinction between the term "careless" or "reckless" operation depends on whether to recognize the given situation. Some incidents happened by failing to aware NOTAM, violating ATC, or T/W landing where a pilot did not recognize the violation itself are considered to be "Careless" flight. Others such as low altitude high speed flight, approximate flight, Rejecting ATC instruction where a pilot intends to or is remiss in safety are regarded as "Reckless" flight. For pilots who are required to take the highest level of care from preparing for flight to stopping engines or completely disembarking passengers from a plane, the clear understanding of the most basic concept of "careless" or "reckless" flight should be emphasized for the safe flight and it is the time for the authorities to set a standard for proper measures by definite legal interpretations.

• 항공우주산업기술동향
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• 제8권1호
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• pp.62-76
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• 2010

본 논문에서는 최근에 다른 나라에서 진행된 무인 달 착륙선의 설계에 대한 사례 조사를 수행하고 이를 통하여 무인 달 착륙선의 설계 동향을 파악하였다. 무인 달 착륙선으로는 일본의 SELENE-2, 유럽의 LEDA와 MoonNEXT, 미국의 모듈형 소형 우주선을 이용한 달 탐사, 그리고 미국이 제안한 국제 달 탐사 네트워크의 미국 노드인 Anchor Nodes의 임무 수행을 위하여 설계된 달 착륙선 등을 조사의 대상으로 하였다. 각 조사 대상의 착륙선에 대하여 임무 요구 조건을 확인하고, 임무 설계의 내용을 조사하였다. 또한 달 표면에 안전하게 착륙하기 위한 유도제어의 방법, 센서의 구성, 임무 요구 사양을 만족하기 위하여 선정한 센서 및 구동기의 성능 사양 등을 분석하였다.

• 한국항공운항학회지
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• 제24권3호
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• pp.62-68
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• 2016

According to the accident/incident reports of aircraft runway overruns and excursions, it generally shows runway friction reduction and aircraft braking capability deterioration are the basic causes due to adverse weather. Although surface of paved runway gets wet, it also should give good friction capability. If runway surface is worn due to long time usage and friction capability is reduced due to rubber accumulation or weather conditions(snow, rain, ice etc.), airport authorities should rapidly measure friction coefficient and give them to relevant persons through aeronautical information system and support safe takeoff and landing. Operation wise, these information of friction coefficient reduction should be lead to aircraft performance adjustments, but the data from manufacturer(performance manual) are airplane braking coefficient and the data from airport authorities are vehicle measured braking coefficient. But these two data are considered as the same meaning although the definite relationship between them is not clarified yet. So I am trying to search for the technical background of these two data and suggest reasonable method to use them efficiently.

• 한국추진공학회지
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• 제9권3호
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• pp.60-65
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• 2005

본 연구는 기존의 폭발볼트와는 달리 작동에 필요한 전원의 공급 없이 수행하면서, 또한 지연기능까지 포함한 비전기식 지연형 폭발볼트에 관한 것이다. 즉 비전기식 작동방법을 이용하여 전원 공급 장치를 없앨 수 있기 때문에 분리장치의 소형화가 가능해졌고, 이를 위하여 기존 폭발볼트의 작동 메카니즘과는 다른 새로운 개념의 메카니즘을 적용하였고, 또한 지연기능을 추가하기 위하여 작동 메카니즘 개발과 별도로 지연장치를 개발하였다. 전원을 사용하지 않고 작동하는 착화장치를 설계하기 위하여 폭발볼트가 결합된 비행체에서 발생하는 공기의 저항력을 이용하였다. 고속으로 비행하는 발사체의 속도를 줄이고 안전한 착륙을 위한 낙하 시스템의 설계에 고려될 수 있는 장치라고 생각된다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.499-505
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• 2004

A Propulsion System of the CRW(Canard Rotor Wing) type UAV(Unmanned Aerial Vehicle) was composed of the turbojet engine to generate the propulsive exhaust gas, and the duct system including straight bent ducts, tip-jet nozzles, a master valve and a variable main nozzle for three flight modes such as lift/landing mode, low speed transition flight mode and high speed forward flight mode. In this study, in order to operate safely the propulsion system, the dynamic Performance behavior of the system was modeled and simulated using the SIMULIN $K^{ }$, which is the user-friendly GUI type dynamic analysis tool provided by MATLA $B^{ }$. In the transient performance model, the inter-component volume model was used. The performance analysis using the developed models was performed at various flight condition, valve angle positions and fuel flow schedules, and these results could set the safe flight mode transition region to satisfy the inlet temperature overshoot limitation as well as the compressor surge margin. Performance analysis results using the SIMULIN $K^{ }$ performance program were compared with them using the commercial program GSP.m GSP.

• International Journal of Naval Architecture and Ocean Engineering
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• 제13권1호
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• pp.734-745
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• 2021

In order to achieve a good and competitive FPSO design, the building cost and the motion performances are the two most critical and conflicting KPIs to be considered. In this study, the author's previous work (Lee, et al., 2021) on the optimization of an FPSO's hull dimensions with 1800 MBBLs storage capacity at Brazil field was extended using a multi-objective parametric optimization with the hull steel weight and the operability which are closely related to the building cost and the operational cost during the lifetime, respectively. For the purpose of more realistic and practical FPSO design, the constraints related to crew comfort and the safe helicopter take-off and landing operation were newly added. Also, the green water on deck was calculated accurately to check the suitability of the designed freeboard height using a newly developed real-time calculation module for the relative wave elevations. With aids of this updated optimization formulation, we presented multiple optimal FPSO dimensions expressed as a Pareto set which aids FPSO designers to conveniently select the practical and competitive dimensions. The excellence of the developed approach was verified by comparing the optimization results with those of FPSOs dimensioned for operation at West Africa and Brazil field.

• 한국항공운항학회지
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• 제31권2호
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• pp.100-107
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• 2023

This study intends to present the UAM pilot qualifications and training and education systems based on the roadmap of technology for K-UAM operation system, which is being promoted for commercialization in 2025. There are currently about 250 eVTOL manufactures around the world, and they are gearing up to produce a variety of UAM aircrafts. In Korea, 35 companies including Hyundai Motor company, Korean Air, Lotte and SKT are accelerating the development of UAM aircrafts. UAM is being developed as a public goods concept centered on public transportation and urban aviation rather than private transportation. Therefore, the UAM pilot qualification and education and training system should be suitable for operations in densely populated areas and complex urban enviroments. In other words, in order to ensure safe UAM operations, the competencies and qualifications of UAM pilots should be clearly established.

• 한국항공우주학회지
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• 제50권9호
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• pp.599-608
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• 2022

로터 시스템을 사용하는 도심 항공 모빌리티(Urban Air Mobility, UAM)는 이착륙 시 버티포트(Vertiport)에서 지면 효과를 경험하게 된다. UAM의 안전한 운용을 위해서는 지면 효과가 비행체의 공력성능에 미치는 영향성이 선행적으로 분석되어야 한다. 본 연구에서는 Lattice Boltzmann Method (LBM)를 적용하여지면 효과가 동축 반전 프로펠러를 장착한 쿼드콥터 형상 전기동력 수직이착륙기 전기체의 공력성능 및 후류 구조에 미치는 영향을 분석하였다. 동축 반전 프로펠러 시스템의 상하부 프로펠러에서 지면 효과 영향성은 상이하게 관찰되었다. 지면과의 이격 거리가 변화하더라도 상부 프로펠러의 성능에는 큰 변화가 없었지만, 지면과 가까워질수록 하부 프로펠러에서는 평균 추력과 토크 값이 크게 증가하였다. 또한 이격 거리가 감소함에 따라 추력 변동의 진폭이 증가하는 경향성이 나타났다. 지면 효과에 의해 프로펠러 후류는 하류 방향으로 충분히 전파되지 못하고 지면을 따라 발달한 Outwash 흐름에 의해 확산되었다. 프로펠러 시스템 사이에서 지면 확산 유동이 충돌하는 분수 와류(Fountain Vortex)의 형성을 확인하였다.