• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.4
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• pp.64-69
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• 2002

Dynamic analysis of laminated beams with a embedded damping layer under tension or compression axial load is investigated. Improved Layer-Wise Zig-Zag Beam Theory and Interdependent Kinematic Relation using the governing equations of motion are incorporated to model the laminated beams with a damping layer and a corresponding beam zig-zag finite element is developed. Flexural frequencies and modal loss factors under tension or compression axial load are calculated based on Complex Eigenvalue Method. The effects of the axial tension and compression load on the frequencies and loss factors are discussed.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.8
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• pp.12-19
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• 2004

Low-speed gas flows around a micro-scale flat plate are investigated using a kinetic theory analysis. The Boltzmann equation simplified by a collision model is solved by means of a finite difference approximation with the Discrete Ordinate method. Calculations are made for flows around a 5% flat plate with a finite length of 20 microns. The results are compared with those from the Information Preservation method and a continuum approach with slip boundary conditions. It is shown that three different approaches predict a similar basic flow patterns, while the results from the present method are more accurate than those from the other two methods in details.

• Aerospace Engineering and Technology
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• v.11 no.2
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• pp.182-194
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• 2012

To develop a liquid rocket engine with high reliability and safety under constraints of limited time and budget an optimal diagnosis system for the engine needs to be developed in parallel with the development of the engine. This paper is intended to set a development direction of the diagnosis system for the liquid rocket engine through the literature survey and addresses possible engine defects, characteristics of parameters for diagnosis and diagnostic methods including real-time diagnosis, post-test/post-flight diagnosis, fault detection method, parameter circuit method and test diagnosis. In addition tasks to be performed in the design and operation phases of the engine and foreign application case of engine diagnosis are presented.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.2
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• pp.122.1-122.1
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• 2014

다가오는 거대마젤란망원경 (GMT) 시대를 이끌어갈 신진 연구자들의 연구역량 증진을 위해, 2014년 8월 25일부터 29일까지 4박5일에 걸쳐 경상북도 경주시 대명리조트에서 제4회 거대마젤란망원경 여름학교를 개최하였다. 총 40명이 학생으로서 참가한 이번 여름학교에서는 다음과 같은 두 가지 새로운 프로그램이 시도되었다. (1) 관측천문학의 기초, 우리은하 천문학의 기초, 외부은하 천문학의 기초 등 세 번의 기초강의를 선택적으로 제공하였다. (2) 별과 행성, 항성종족과 화학진화, 은하 형성, 고적색이동 천체와 재이온화, 우주론 등 총 다섯 개 분야에서 심화강의를 제공한 뒤에 각 강의내용과 연관된 열린 질문들을 화두로 해서 학생들 간에 조별 토론을 진행하였다. 이는 정해진 답이 없는 문제를 놓고 토론을 통해 능동적으로 답을 찾아가는 과정을 훈련하기 위해 고안된 것이다. 본 포스터에서는 제4회 거대마젤란망원경 여름학교의 결과를 정리하고 앞으로 나아갈 GMT 계절학교의 방향을 점검해본다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.5
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• pp.446-451
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• 2007

Since the introduction of advanced composite materials for use in aircraft, the material qualification has been a costly burden to the small airframe manufacturer. For each manufacturer, extensive qualification testing has often been performed to develop the base material properties and allowables at operating environmental conditions, regardless of whether this material system had been previously certificated by other manufacturers. In recent years, NASA, industry, and the FAA have worked together to develop a cost-effective method of qualifying composite material systems by the sharing of a central material qualification database. In this paper, the new methodology of composite material qualification is presented and material allowable of 350°F carbon fiber/epoxy composite material produced domestically is determined with this methodology.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.7
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• pp.581-593
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• 2017

In order to develop high efficiency propeller for multicopter type UAV, we designed, analyzed and tested aerodynamic and structural dynamics. For the design of the high efficiency propeller, the optimum design method was applied for the determination of the airfoil and the three-dimensional planform is designed to reduce induced power of the propeller. The flight suitability of the derived shape was determined through structural design and analysis. The rotation test was performed to confirm the performance of the analytically designed shape. In this paper, we propose a procedural propeller design methodology using these design analysis test methods.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.5
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• pp.335-341
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• 2013

The variation of systematic bias errors in the wind tunnel testing has been studied. A Design of Experiments(DOE) approach to an experimental study of fuselage drag and stability characteristics of a helicopter configuration was applied. When forces and moments measured in one time block differ significantly from measurements made in another time block under assumption that sample observations can be expected to yield same results within permissible measuring errors. The practical implication of this paper is that the systematic error can not be assumed not to exist. The those error reduction could be achieved through the process of randomization, blocking, and replication of the data points.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.8
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• pp.24-32
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• 2006

Using a deterministic design optimization, the effect of uncertainty can result in violation of constraints and deterioration of performances. For this reason, design optimization is required to guarantee reliability for constraints and ensure robustness for an objective function under uncertainty. Therefore, this study drew Monte Carlo Simulation(MCS) for the evaluation of reliability and robustness, and selected an artificial neural network as an approximate model that is suitable for MCS. Applying to the aero-structural optimization problem of aircraft wing, we can explore robuster optima satisfying the sigma level of reliability than the baseline.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.4
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• pp.378-384
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• 2011

During the flight test of KSLV-I, various sensors are installed in the launch pad and the flame deflector to measure the flame characteristics and their influences on the launch complex when a launch vehicle lifts off. Parameter Measurement System is responsible for acquiring the above flight test data. The measurement methodology such as the configuration of measurement system, sensor locations and data acquisition procedures are presented. And this paper compares and explains the characteristics of data sets measured during two flight tests.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.4
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• pp.291-297
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• 2014

A Design of Experiments(DOE) approach to an experimental study of fuselage drag and stability characteristics of a helicopter configuration was applied to achieve an accuracy improvement in the wind tunnel testing. The impact of blocking the test was assessed by comparing the ANOVA table for the blocked and unblocked cases. For a second-order response model, the role of blocking resulted in a substantial increase in the accuracy of test results. These accuracy improvement could be achieved through randomization, blocking, and replication of the data points i.e. a re-ordering of the test sequence where the data were acquired.