• 항공우주기술
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• 제6권1호
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• pp.165-172
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• 2007

우주 발사체는 수많은 부품으로 이루어져 있기 때문에 개발 성공을 위해서는 사소한 부품 하나라도 그 기능을 제대로 발휘하고 고장이 없어야 한다. 이를 위해서 우주 발사체용 부품 및 시스템 개발에는 수많은 시험을 수행하게 된다. 일반적으로 번인시험(burn-in test)은 생산된 제품이 재질이나 작업자의 미숙에 의해 초기 사용기간 중 발생될 수 있는 고장요인을 찾아내기 위한 시험을 통칭한다. 해외 선진국의 경우 번인시험에 대해 규격으로 기술하고 있으며 이에 따라 시험을 수행한다. 본 논문에서는 KSLV-I과 같이 국내에서 개발될 우주 발사체용 부품에 대한 번인시험 적용방법에 대해 고려해 보고자 한다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.393-396
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• 2008

Propellant consumption control for space launch vehicle can be achieved by propellant utilization system (PUS) and tank depletion system (TDS). In the course of developing new space launch vehicles, the main target of design is on reducing of space launch vehicle weight, which results in increasing both specific impulse and payload weight. The weights of space launch vehicles are generally allocated to structure, propulsion system, and propellants loaded. The quantity of propellants filled in propellant tanks may be estimated with the propellants actually consumed by propulsion system to complete its mission and the propellants left on-board at the time of engine shut-off. To minimize the remaining quantity of propellants on-board the supplying propellants' O/F ratio should be controlled from the certain time before engine shutdown. To control an O/F ratio, a control system, which accurately measures and compares the remainder of propellants in tanks and pipes, should be needed. This paper solely dedicates its contents to explore the merits and demerits of various level sensor, which is one of the important elements for PUS and TDS, and the transmission and control of signals within space launch vehicle.

• International Journal of Aeronautical and Space Sciences
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• 제18권3호
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• pp.485-497
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• 2017

The pogo phenomenon refers to a type of multidiscipline-related instability found in space launch vehicles. It is caused by coupling between the fuselage structure and other structural propulsion components. To predict the pogo phenomenon, it is essential to undertake adequate structural modeling and to understand the characteristics of the feedlines and the propulsion system. To do this, a modal analysis is conducted using axisymmetric two-dimensional shell elements. The analysis is validated using examples of existing launch vehicles. Other applications and further plans for pogo analyses are suggested. In addition, research on the pogo phenomenon of Saturn V and the space shuttle is conducted in order to constitute a pogo stability analysis using the results of the present modal analysis.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2011년도 제36회 춘계학술대회논문집
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• pp.179-182
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• 2011

비행축/자세제어용 단일추진제 추력기의 우주발사체 적용과 국내 설계개발 현황을 조사/분석하였다. 탑재체의 정확한 궤도투입을 위하여 정밀한 자세제어가 요구되는 발사체 최종 단은 대부분 비추력 성능이 우수하고 높은 신뢰도 확보가 가능한 단일추진제 하이드라진 추력기시스템을 장착한다.

• 한국융합학회논문지
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• 제11권10호
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• pp.71-79
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• 2020

최근 주거가치의 변동으로 인해, 주거공간 내에서의 다양한 공간에 대한 사용자 니즈가 커지고 있다. 하지만, 이동과 변형 등이 어려운 주거공간 특성상 최초 구성된 주거 형태를 사용자의 필요에 따라 변경하고 재구성하기가 쉽지 않다. 이에 본 연구는 이동이 가능한 공간 개념의 완전 자율주행 자동차를 활용하여 변화하는 주거가치에 따른 사용자 니즈를 충족시킬 방안을 도출하고자 하였다. 먼저 문헌연구를 통해 기존 주거공간을 유형화하였으며, 이를 토대로 사용자 연구를 통하여 주거를 위한 완전 자율주행 자동차의 공간 유형을 도출하였다. 그 후 설문조사법과 통계적 분석을 통해 주거공간에 대한 사용자 니즈 분석과 도출된 공간 유형의 유용성 분석 및 유형 구체화를 진행하였다. 마지막으로 연구결과를 토대로 주거를 위한 완전 자율주행 자동차의 디자인 방향성을 제시하였다. 사용자의 인식을 바탕으로 주거목적의 완전 자율주행 자동차의 공간을 유형화하고 디자인 방향성을 제안하였다는 점에서 의의가 있다.

• 시스템엔지니어링워크숍
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• 통권6호
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• pp.134-137
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• 2005

• 한국항공우주학회지
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• 제32권8호
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• pp.151-160
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• 2004

• 한국정밀공학회지
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• 제19권1호
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• pp.127-134
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• 2002

This study present a direct steering system using rack and pinion for ultra-small vehicles. The traditional small vehicles for special use had the limitation of space by reason of short wheel tread. These vehicles has adopted a indirect steering system or a center arm system for steering. The disadvantages of these system were deterioration of gear efficiency and increase of parts. For direct-linkage to both knuckles, steering system is made up of out-side tie rods, tie-rod ends, and gear box. Thus, the proposed system has a minimum number of parts. The experimental results show a maximum efficiency at minimum steering angle and a minimum clearance circle. These effects were accomplished by adopting a Ackerman-Jantaud theory.

• KEPCO Journal on Electric Power and Energy
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• 제6권1호
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• pp.59-64
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• 2020

Scheduling of electric vehicles and optimizing for charging waiting time have been critical. Meanwhile, it is challengeable to exploit the fluctuating data from electric vehicles in real-time. We introduce an optimal routing algorithm and a simulator with electric vehicles obeying the Poisson distribution of the observed information about time, space and energy-demand. Electric vehicle routing is updated in every cycle even it is already set. Also, we suggest an electric vehicle routing algorithm for minimizing total trip time, considering a threshold of the waiting time. Total trip time and charging waiting time are decreased 34.3% and 86.4% respectively, compared to the previous algorithm. It can be applied to the information service of charging stations and utilized as a reservation service.

• 한국해양공학회지
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• 제36권1호
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• pp.41-49
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• 2022

With the advancement of intelligent vehicles and unmanned systems, there is a growing interest in underwater surveys using autonomous marine vehicles (AMVs). This study presents an automated planning strategy for a long-term survey mission using a fleet of AMVs consisting of autonomous surface vehicles and autonomous underwater vehicles. Due to the complex nature of the mission, the actions of the vehicle must be of high-level abstraction, which means that the actions indicate not only motion of the vehicle but also symbols and semantics, such as those corresponding to deploy, charge, and survey. For automated planning, the planning domain definition language (PDDL) was employed to construct a mission planner for realizing a powerful and flexible planning system. Despite being able to handle abstract actions, such high-level planners have difficulty in efficiently optimizing numerical objectives such as obtaining the shortest route given multiple destinations. To alleviate this issue, a widely known technique in operations research was additionally employed, which limited the solution space so that the high-level planner could devise efficient plans. For a comprehensive evaluation of the proposed method, various PDDL-based planners with different parameter settings were implemented, and their performances were compared through simulation. The simulation result shows that the proposed method outperformed the baseline solutions by yielding plans that completed the missions more quickly, thereby demonstrating the efficacy of the proposed methodology.