• 한국항행학회논문지
• /
• 제15권3호
• /
• pp.432-440
• /
• 2011

본 논문에서는 위성항법 기반 교통인프라에서 제공되는 정보를 이용하여 차로 구분에 적용할 때 차로 구분 성능을 향상시키기 위한 차로 제한 조건을 제시하고 시뮬레이션을 통하여 성능을 검증하였다. 차로 제한 조건은 차량의 진행 방향과 차량이 위치하고 있는 차로의 관계를 이용하여 1차로와 마지막 차로의 차로 구분 임계치를 크게 설정하여 차로 구분 성공률을 향상시키는 기법이다. 시뮬레이션 결과 차로 제한 조건을 사용할 경우 4차로에서는 40%, 6차로에서는 25%, 8차로에서는 15%의 성능차로 구분 성능이 향상됨을 확인하였다.

• Composites Research
• /
• 제28권6호
• /
• pp.402-407
• /
• 2015

It is well known that the polymer matrix composite materials have good specific strength, making them appropriate for use in transport vehicle. Since the property of composite materials can be obtained only after manufacturing parts, the property depends on greatly on the fabrication process, which is different from metallic system. Therefore, in order to use composite materials for aircraft, the certifying agency requires a robust database with extensive tests and proof of the process unlike metals. Recently developed material qualification methodology by NCAMP (National Center for Advanced Materials Performance) has been accepted by FAA and EASA and can be applied to type certificate reducing time and cost of developing a composite materials database for aircraft application. This paper summarizes a study to establish the composite materials database to apply the NCAMP methodology to composite materials characterization for composite aircraft and to provide the effective materials database through Aerospace Composite Materials Data Center to be approved by Korea Civil Aviation Certification Agency.

• 한국추진공학회지
• /
• 제18권6호
• /
• pp.50-58
• /
• 2014

본 논문에서는 우주발사체용 액체로켓엔진의 건전성 감시 및 관리 기법에 대한 연구 동향을 소개한다. 이를 위하여 미국, 유럽, 러시아와 같은 우주선진국에서 실제 우주발사체용 액체로켓엔진에 연구 및 적용되었던 고장진단 알고리즘을 조사하였다. 특히 최근 우주선진국으로 발돋움하고 있는 중국에서 적용한 기술들을 중심으로 조사하였으며 적용된 사례들을 분석하여 특징들을 나열하였다. 이를 통하여 한국형발사체 KSLV-II 및 그 후의 한국형 달탐사선 발사체 개발사업에 적용하기 위해 고려해야 할 사항에 대하여 토의한다.

• Journal of Astronomy and Space Sciences
• /
• 제41권1호
• /
• pp.43-60
• /
• 2024

Korea Pathfinder Lunar Orbiter (KPLO) is South Korea's first space exploration mission, developed by the Korea Aerospace Research Institute. It aims to develop technologies for lunar exploration, explore lunar science, and test new technologies. KPLO was launched on August 5, 2022, by a Falcon-9 launch vehicle from cape canaveral space force station (CCSFS) in the United States and placed on a ballistic lunar transfer (BLT) trajectory. A total of four trajectory correction maneuvers were performed during the approximately 4.5-month trans-lunar cruise phase to reach the Moon. Starting with the first lunar orbit insertion (LOI) maneuver on December 16, the spacecraft performed a total of three maneuvers before arriving at the lunar mission orbit, at an altitude of 100 kilometers, on December 27, 2022. After entering lunar orbit, the commissioning phase validated the operation of the mission mode, in which the payload is oriented toward the center of the Moon. After completing about one month of commissioning, normal mission operations began, and each payload successfully performed its planned mission. All of the spacecraft operations that KPLO performs from launch to normal operations were designed through the system operations design process. This includes operations that are automatically initiated post-separation from the launch vehicle, as well as those in lunar transfer orbit and lunar mission orbit. Key operational procedures such as the spacecraft's initial checkout, trajectory correction maneuvers, LOI, and commissioning were developed during the early operation preparation phase. These procedures were executed effectively during both the early and normal operation phases. The successful execution of these operations confirms the robust verification of the system operation.

• 한국항공우주학회지
• /
• 제49권1호
• /
• pp.41-52
• /
• 2021

발사체가 대기 중에서 상승 비행 시 공기역학적 현상에 기인한 음향하중을 받는데 천음속 영역에서 그 영향이 커진다. 본 연구에서는 천음속 조건에서 해머헤드 발사체 외부에 작용하는 음향하중을 ��-ω SST 난류모델 기반 IDDES 법으로 해석하여 시간 평균 압력계수, 표면 압력섭동, 압력섭동 파워 스펙트럼을 분석하고 가용한 풍동실험 데이터와 비교하였다. IDDES 결과의 격자 의존성을 검토하였으며, 난류 스케일 분해가 가능한 적절한 계산격자를 사용한 경우 천음속 헤머헤드 발사체의 특징적인 유동 현상인 페어링 어깨에서의 유동 박리와 박리 유동의 후방 동체 재 부착, 보트 테일 후방에서의 높은 압력섭동을 공학적으로 유의미한 정확도로 예측 가능함을 확인하였다.

• Tribology and Lubricants
• /
• 제22권6호
• /
• pp.329-334
• /
• 2006

In CNG (Compressed natural gas) fuel supply line, whose main components are receptacle and check valve are used to charge high pressure gas to the tank of NGV (Natural gas vehicle). It is reported that the seal is separated occasionally form valve seat and results in blockage of gas flow. In this paper, MARC is used to investigate the reasons of seal separation and suggest design improvements. The static gas pressure distributions acting on the seal which calculated using FLUENT are considered to investigate accurate seal deformation behaviors. Deformed seal shapes are obtained for various amounts of seal interference and its location, gas pressure distributions and Young's modulus of the rubber used. The results showed that the reasons of seal separation problems are verified theoretically, and suggested examples of new design method. Therefore the present numerical methods can be applied in designing and performance analysis of rubber seals adopted in high pressure fluid machineries.

• International Journal of Aeronautical and Space Sciences
• /
• 제14권1호
• /
• pp.75-84
• /
• 2013

In this paper, the guidance law for formation flight and collision avoidance of multiple Unmanned Aerial Vehicle (UAV)s is proposed. To construct the physically comprehensible guidance law for formation flight, the virtual structure approach is used. To develop a guidance law for collision avoidance considering both other UAVs and unknown static obstacles, a geometric approach using information such as a relative position vector is utilized. Through the Lyapunov theorem, the stability of the proposed guidance law is proved. To combine guidance commands, the concept of the elastic weighting factor inspired by the elastic behavior of shape memory polymer, which tends to regain its original shape after deformation, is introduced. By using the concept of elastic weighting factor, multiple UAVs are able to cope actively with the situation of a collision between both UAVs and static obstacles during the formation flight. To verify the performance of the proposed method, numerical simulations are performed.

• 항공우주기술
• /
• 제9권2호
• /
• pp.198-203
• /
• 2010

KSLV-I 나로호는 대한민국 최초의 위성발사체로 러시아와 공동개발 되었다. 2009년 8월에 이루어진 1차 발사는 위성을 궤도로 올리려는 목표 달성에는 실패하였지만 발사를 안전 관점에서 보았을 때는 사고 없이 안전하게 이루어졌다. 2010년 6월의 2차 발사에서도 인명이나 시설 손상과 같은 사고는 없었다. 이러한 안전한 발사를 이루기 위하여 우주발사체 사업단은 흐루니체프사와의 협력을 통해 발사체 안전 프로그램을 개발한 바 있다. 본 논문에서는 안전 관리 프로그램에 속해있는 각종 분석들과 그 내용들을 소개하고자 한다.

• International Journal of Aeronautical and Space Sciences
• /
• 제18권4호
• /
• pp.662-674
• /
• 2017

This paper describes the multidisciplinary design optimization (MDO) process of a tailless unmanned combat aerial vehicle (UCAV) using global variable fidelity aerodynamic analysis. The developed tailless UAV design framework combines multiple disciplines that are based on low-fidelity and empirical analysis methods. An automated high-fidelity aerodynamic analysis is efficiently integrated into the MDO framework. Global variable fidelity modeling algorithm manages the use of the high-fidelity analysis to enhance the overall accuracy of the MDO by providing the initial sampling of the design space with iterative refinement of the approximation model in the neighborhood of the optimum solution. A design formulation was established considering a specific aerodynamic, stability and control design features of a tailless aircraft configuration with a UCAV specific mission profile. Design optimization problems with low-fidelity and variable fidelity analyses were successfully solved. The objective function improvement is 14.5% and 15.9% with low and variable fidelity optimization respectively. Results also indicate that low-fidelity analysis overestimates the value of lift-to-drag ratio by 3-5%, while the variable fidelity results are equal to the high-fidelity analysis results by algorithm definition.

• 한국추진공학회지
• /
• 제24권2호
• /
• pp.61-72
• /
• 2020

국외에서 개발이 진행되고 있거나 완료된 UAV에 적용된 추진기관의 성능 특성을 분석하였다. 본 연구에서 총 10종의 UAV의 임무 및 성능 특성을 검토하고 민간항공기 및 군용항공기와 성능 특성을 비교 검토하였다. 또한, UAV 추진기관의 성능 특성을 정리하고 엔진 설계 파라미터에 대한 분석을 수행하였다. 추진기관의 추력, SFC 및 설계변수인 압축비, 바이패스비에 대해 민간 및 군용항공기 엔진과 비교하여 검토하였으며, 본 연구를 통해 UAV에 따른 설계 파라미터를 보다 잘 이해할 수 있었다.