• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.581-582
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• 2010

• Transactions of the KSME C: Technology and Education
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• v.2 no.2
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• pp.113-124
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• 2014

In developing an aircraft, configuration determination and requirement proofing depend on flight test results. Since the flight tests require much time and high cost, systematic flight test planning and analysis are needed to reduce cost and development time. This paper presents a desirability function approach to present an integrative measure of vibration levels at important positions and suggests a fractional factorial design which is one of the experimental design methods to help perform systematic flight tests. A method to perform flight tests in stages is also suggested to further reduce the number of flight tests.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.9
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• pp.931-938
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• 2009

The flight test is last means of compliance to satisfy airworthiness standards and important to evaluate the performance and safety of the developed aircraft. The flight test technologies are obtained from great numbers of experiences and know-hows and protected. In addition, flight test should be conducted efficiently since its various test conditions and items. Therefore, it is requisite to secure efficient flight test methods. This paper discusses the flight test methods for take-off and landing performance and two kinds of techniques are proposed. By performing real flight tests, they are compared with each other and analyzed through the flight analysis.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.76-76
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• 1999

한국자원연구소 제작된 TOF spectrometer는 입자의 비행시간과 에너지를 동시에 측정 기록하여 질량분별된 에너지 스펙트럼을 얻고자 하는 목적으로 제작되었다. 그러나 질량분별이 필요치 않은 후방 산란실험에서는 비행시간의 측정만으로 훌륭한 에너지 계측기가 된다. 중이온 산란분석법(heavy ion RBS)은 He을 사용하는 산란분석법에 비하여 원리적으로 분해능이 우수하나 사용하는 반도체 검출기의 에너지 분해능의 불량이 이러한 장점을 상쇄하는 실정이다. 그러나 TOF spectrometer를 중이온 산란실험의 에너지 계측기로 사용하면 H, He에 대한 반도체 검출기 정도의 낮은 에너지분해능 수준을 유지할 수 있으므로 중이온 산란실험의 원리적인 장점을 살릴 수 있다. 한국자원연구소에서는 He RBS의 취약점으로 지적되어온 medium elements에 대한 질량분해능과 깊이 분해능을 향상시키고자 140$^{\circ}$ 산란각에 TOF spectrometer가 위치하는 Heavy Ion Rutherford Backscattering Spectrometry (HIRBS) 시스템을 설계하였다. 설계된 TOF spectrometer를 채용하였을 때 기대되는 질량분해능 향상효과와 분석의 최적조건에 관하여 논한다.

• Bulletin of the Korean Space Science Society
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• 2009.10a
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• pp.49.2-49.2
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• 2009

소형우주발사체 KSLV-I의 상단부 전자장비 탑재 구조체의 외부면에는 텔레메트리, 원격추적, GPS, 비행종단 시스템의 안테나가 두 개 또는 세 개씩 장착된다. 발사체의 표면에 안테나를 부착할 수 있는 위치는 제한되어 있기 때문에 각 안테나 들은 서로 인접되어 부착된다. 또한 상단부 전자장비들과 지상장비의 성능을 검증하기 위해 수행되는 경비행기를 이용한 비행시험은 각 안테나들이 더욱 근접하여 장착된 상태로 수행된다. 따라서 각 하부시스템의 안테나 사이에 발생하는 간섭현상을 분석하기 위한 연구가 요구된다. 이 논문에서는 시간영역 유한차분법을 이용하여 서로 다른 하부시스템의 안테나 간에 발생하는 간섭영향을 해석하였다. 수행된 해석 과정은 우주발사체의 안테나 방사패턴을 해석하는데 이용될 수 있으며, 향후 우주발사체의 시스템 설계 과정에서 안테나의 배치 방법과 각 하부시스템의 성능 요구조건을 결정하는데 효과적으로 사용될 수 있다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.5
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• pp.46-55
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• 2006

In general, 3-dimensional point-mass equation has been widely used for the trajectory optimization of the fixed-wing aircraft and reentry vehicle. But it should be modified and represent target vehicle's own characteristics. For a lighter-than-air vehicle such as an airship, there exists different and peculiar flight characteristics compared with the aircraft. The first part of this paper is to derive the dynamic equation of motion for the mid-altitude unmanned airship and the second part is to obtain the optimal trajectories under the minimal time flight given constraints. The trajectory optimization problem is converted into the nonlinear programming problem using Sequential Quadratic Programming approach. Finally numerical solutions are presented in the last part of the paper.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.6
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• pp.519-526
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• 2009

This paper describes a research result of a external shape optimization study to maximize the range of the guided missile with canards and tailfins in atmospheric flight. For this purpose, the external shape optimization program which can enhance the range of a missile was developed, incorporated with the trajectory analysis and the optimization technique. In the trajectory analysis part, Missile DATCOM which utilizes the semi-empirical method was directly connected to the trajectory code to supply the aerodynamic coefficients efficiently at every time step. In the gliding flight trajectory after apogee, a maximum $C_L/C_D$ trim condition calculation module was attached under the assumption of the missile continuously flying at maximum $C_L/C_D$ condition. In the optimization part, a Response Surface Method(RSM) was adopted to reduce the computing time.

• Journal of the Korean Society of Radiology
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• v.7 no.3
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• pp.245-249
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• 2013

Neutron sources from photonuclear reaction with 46-MeV electron linear accelerator at Research Reactor Institute, Kyoto University used for resonance energy measurement of natural tantalum. BGO($Bi_4Ge_3O_{12}$) scintillation detectors used for measurement of the prompt gamma ray from the natural tantalum sample. The BGO spectrometer was composed geometrically as total energy absorption detector. The electric signal from the spectrometer was analyzed for TOF(Time-of-Flight) spectrum which is used identification of neutron capture resonance energy. In this study, the neutron energy region is from 1 to 200 eV, because of strong X-ray effect produced photonuclear reaction in Ta target, the measurement was performed to below 1 keV energy region. The resonance energy was compared with the evaluated values(ENDF/B-VI, Mughabghab). All of the resonances from 4.28 ~ 200 eV were seen in the present measurement except 144.3 eV resonance.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.11a
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• pp.141-142
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• 2008

• Aerospace Engineering and Technology
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• v.4 no.1
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• pp.186-195
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• 2005

This paper deals with attitude control design for a thruster system which is mainly used as a control system of space vehicles. Attitude controllers are designed based on a simple blowing-down thruster system structure. In order to consider severe time-delay effects of the thruster system during controller design, the control design problem is defined based on the corresponding limit cycle analysis. Optimal roll controllers and optimal pitch/yaw controllers are resulted from co-evolutionary optimum design processes for each flight phase. The control performances are verified by computer simulations.