• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년 영문 학술대회
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• pp.330-339
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• 2008

Ground-based interceptors(GBI) comprise a major element of the strategic defense against hostile targets like Intercontinental Ballistic Missiles(ICBM) and reentry vehicles(RV) dispersed from them. An optimum design of the subsystems is required to increase the performance and reliability of these GBI. Propulsion subsystem design and optimization is the motivation for this effort. This paper describes an effort in which an entire GBI missile system, including a multi-stage solid rocket booster, is considered simultaneously in a Genetic Algorithm(GA) performance optimization process. Single goal, constrained optimization is performed. For specified payload and miss distance, time of flight, the most important component in the optimization process is the booster, for its takeoff weight, time of flight, or a combination of the two. The GBI is assumed to be a multistage missile that uses target location data provided by two ground based RF radar sensors and two low earth orbit(LEO) IR sensors. 3Dimensional model is developed for a multistage target with a boost phase acceleration profile that depends on total mass, propellant mass and the specific impulse in the gravity field. The monostatic radar cross section (RCS) data of a three stage ICBM is used. For preliminary design, GBI is assumed to have a fixed initial position from the target launch point and zero launch delay. GBI carries the Kill Vehicle(KV) to an optimal position in space to allow it to complete the intercept. The objective is to design and optimize the propulsion system for the GBI that will fulfill mission requirements and objectives. The KV weight and volume requirements are specified in the problem definition before the optimization is computed. We have considered only continuous design variables, while considering discrete variables as input. Though the number of stages should also be one of the design variables, however, in this paper it is fixed as three. The elite solution from GA is passed on to(Sequential Quadratic Programming) SQP as near optimal guess. The SQP then performs local convergence to identify the minimum mass of the GBI. The performance of the three staged GBI is validated using a ballistic missile intercept scenario modeled in Matlab/SIMULINK.

• 한국물환경학회지
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• 제32권6호
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• pp.589-599
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• 2016

Implemented since 2004, TPLC (Total Pollution Load Control) is the most powerful water-quality protection program. Recently, uncertainty of prediction using steady state model increased due to changing water environments, and necessity of a dynamic state model, especially the watershed model, gained importance. For application of watershed model on TPLC, it needs to be feasible to adjust the relationship (mass-balance) between discharged loads estimated by technical guidance, and arrived loads based on observed data at the watershed outlet. However, at HSPF, simulation is performed as a semi-distributed model (lumped model) in a sub-basin. Therefore, if the estimated discharged loads from individual pollution source is directly entered as the point source data into the RCHRES module (without delivery ratio), the pollutant load is not reduced properly until it reaches the outlet of the sub-basin. The hypothetic RCHRES generated using the HSPF BMP Reach Toolkit was applied to solve this problem (although this is not the original application of Reach Toolkit). It was observed that the impact of discharged load according to spatial distribution of pollution sources in a sub-basin, could be expressed by multi-segmentation of the hypothetical RCHRES. Thus, the discharged pollutant load could be adjusted easily by modification of the infiltration rate or characteristics of flow control devices.

• 한국항행학회논문지
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• 제21권3호
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• pp.264-271
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• 2017

본 논문에서는 입력된 비행계획을 바탕으로 4차원 궤적을 생성하고, 이 궤적정보를 기반으로 항공기 운동을 나타내는 시뮬레이션 모델을 개발하였다. 4차원 궤적은 BADA에서 제공하는 항공기 성능 계수와 Total Energy Model 및 베지에 곡선을 활용하여 모델링 하였으며, CTA (cntrolled tme of arival) 및 속도를 기준으로 하는 두 가지 항공기 제어 방식을 제안하였다. 시뮬레이션 결과 비행시간 및 경로에 대하여 정의된 궤적과 거의 일치하였으며, 바람 조건에 따른 각 제어 방식 별 차이점을 도출하였다. 본 연구에서 개발된 시뮬레이션 모델을 기반으로, 다양한 항공교통관리 분야 연구에 활용할 수 있을 것으로 기대된다. 향후 연구로 실제 항공기가 운항한 경로와 베지에 곡선간의 차이를 줄이기 위해 최적화 기법을 도입할 필요가 있으며, 이를 통해 개발된 시뮬레이션의 활용도를 높일 수 있다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년 영문 학술대회
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• pp.187-194
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• 2008

Because the types and severities of most engine faults are various and complex, it is not easy that the conventional model based fault detection approach like the GPA(Gas Path Analysis) method can monitor all engine fault conditions. Therefore this study proposed newly a diagnostic algorithm for isolating and diagnosing effectively the faulted components of the smart UAV propulsion system, which has been developed by KARI(Korea Aerospace Research Institute), using the fuzzy logic and the neural network algorithms. A precise performance model should be needed to perform the model-based diagnostics. The based engine performance model was developed using SIMULINK. For the work and mass flow matching between components of the steady-state simulation, the state-flow library was applied. The proposed steady-state performance model can simulate off-design point performance at various flight conditions and part loads, and in order to evaluate the steady-state performance model their simulation results were compared with manufacturer's performance deck data. According to comparison results, it was confirm that the steady-state model well agreed with the deck data within 3% in all flight envelop. The diagnosis procedure of the proposed diagnostic system has the following steps. Firstly after obtaining database of fault patterns through performance simulation, then secondly the diagnostic system was trained by the FFBP networks. Thirdly after analyzing the trend of the measuring parameters due to fault patterns, then fourthly faulted components were isolated using the fuzzy logic. Finally magnitudes of the detected faults were obtained by the trained neural networks. Because the detected faults have almost same as degradation values of the implanted fault pattern, it was confirmed that the proposed diagnostic system can detect well the engine faults.

• 수산해양기술연구
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• 제29권1호
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• pp.39-55
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• 1993

Modal Analysis is the process of characterizing the dynamic properties of an elastic structure by identifying its modes of vibration. A mode of vibration is a global property of an elastic structure. That is, a mode has a specific natural frequency and damping factor which can be identified from response data at practically any point on a structure, and it has a characteristic mode shape which identifies the mode spatially over the entire structure. Modal testing is able to be performed on structural and mechanical structure in an effort to learn more about their elastic behavior. Once the dynamic properties of a structure are known its behavior can be predicted and therefore controlled or corrected. Resonant frequencies, damping factors and mode shape data can be used directly by a mechanical designer to pin point weak spots in a structure design, or this data can also be used to confirm or synthesize equations of motion for the elastic structure. These differential equations can be used to simulate structural response to know input forces and to examine the effects of pertubations in the distributed mass, stiffness and damping properties of the structure in more detail. In this paper the measurement of transfer functions in digital form, and the application of digital parameter identification techniques to identify modal parameters from the measured transfer function data are discussed. It is first shown that the transfer matrix, which is a complete dynamic model of an elastic plate structure can be written in terms of the structural modes of vibration. This special mathematical form allows one to identify the complete dynamics of the structure from a much reduced set of test data, and is the essence of the modal approach to identifying the dynamics of a structure. Finally, the application of transfer function models and identification techniques for obtaining modal parameters from the transfer function data are discussed. Characteristics on vibration response of elastic plate structure obtained from the dynamic analysis by Finite Element Method are compared with results of modal analysis.

• 한국언론정보학보
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• 제58권
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• pp.178-200
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• 2012

커뮤니케이션의 이론연구에서 일반모델에 대한 섬세한 구상은 다양한 형태로 발전되는 커뮤니케이션 현상에 대한 이해를 위해 필요하다. 본 논문은 다양한 이론연구의 유형들 가운데 체계이론의 관점으로 이루어진 커뮤니케이션 모델에 대해 고찰하고, 이 모델에서 특히 중요한 성찰성 개념을 부각시켜보고자 한다. 의미전달과 상호이해의 관점을 중심으로 한 커뮤니케이션 모델에는 여러 가지 논리적인 문제점이 있는데, 본 논문에서는 이러한 문제점들을 주체, 전달, 대화의 패러독스로 정리하였다. 체계이론의 성찰성 개념은 이러한 패러독스의 문제를 해결할 수 있기 때문에 중요하다. 그리고 하버마스의 커뮤니케이션 이론이 패러독스의 문제를 어떻게 풀어가는지 아울러 알아보았는데, 여기에서 언어화용론을 중심으로 한 문제해결 방식에도 역시 논리적인 난점이 있다고 보았다. 따라서 커뮤니케이션학의 관점에서 보았을 때, 루만의 모델은 하버마스의 이론을 보완하는 역할을 한다. 왜냐하면 메르텐으로부터 시작되어 루만, 슈미트 그리고 그랜트에 의해 제시되는 체계이론과 구성주의적 이론은 다른 방식으로 패러독스의 문제를 해결하기 때문이다. 그리고 그 방식을 성찰성으로 개념화할 수 있다. 결국 커뮤니케이션의 합리성론에 대해 비판적인 문제의식에서 출발한 체계이론과 구성주의적 커뮤니케이션 이론은 각각의 경우에 약간의 상이한 점도 나타나지만, 성찰성 개념에 치중하여 커뮤니케이션의 근본적인 문제점들을 해소하는 모델이라고 볼 수 있다.

• 공학논문집
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• 제5권1호
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• pp.89-107
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• 2004

본 연구는 DRASTIC 모델에 구소선밀도, 토지이용 인자를 추가한 수정 DRASTIC 모델을 개발하여 경기도 화남2지구의 지하수오염 가능성을 예측하고자 하였다. 우리나라의 수리지질 환경에서 대수층은 대부분 암반 대수층인 점을 고려했을 때, 구조선밀도는 지하수 및 오염물질 유동에 직접적인 영향을 미치고, 토지이용은 점오염원 혹은 비점오염원의 영향을 간접적으로 반영할 수 있기 때문이다. 통계분석을 위하여 각 인자별 격자 레이어를 생성하고, 각각의 상관계수를 분석함으로써 신뢰도 여부를 판단하였다. 최종 결과물인 종합오염현황도는 수정 DRASTIC Potential과 여러 가지 오염원의 발생 부하량 값을 논리비교함으로써 수리지질학적인 측면에서의 오염가능성 지역과 수질측면에서의 오염가능성 지역을 예측할 수 있는 방안을 제시할 수 있었다.

• International Journal of Air-Conditioning and Refrigeration
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• 제10권3호
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• pp.162-175
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• 2002

To investigate smoke movement with radiation in a room fires, a numerical and experi-mental analysis were performed. In this paper, results from a field model based on a self-developed SMEP (Smoke Movement Estimating Program) were compared with Stockier's ex-periment and the experiments on various sized pool fires in a room with door The SMEP using PISO algorithm solves conservation equations for mass, momentum, energy and species, together with those for the modified k- $\varepsilon$ turbulence model with buoyancy term. Also it solves the radiation equation using the S-N discrete ordinates method (DOM). The result of the cal-culated smoke temperature considering radiation effect has shown good agreement compared with the experimental data, although there are large discrepancy in the hot smoke layer be-tween the temperature predicted by the SMEP with only convection effect and obtained by the experimental result. This large discrepancy is caused from the radiation effect of $H_2O$ and $CO_2$ gas under smoke productions. Hence the radiation effect under smoke in fire is the point to be specially considered in order to produce more realistic result.

• 로봇학회논문지
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• 제3권4호
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• pp.287-299
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• 2008

People have expected a humanoid robot to move as naturally as a human being does. The natural movements of humanoid robot may provide people with safer physical services and communicate with persons through motions more correctly. This work presented a methodology to generate the natural motions for a humanoid robot, which are converted from human motion capture data. The methodology produces not only kinematically mapped motions but dynamically mapped ones. The kinematical mapping reflects the human-likeness in the converted motions, while the dynamical mapping could ensure the movement stability of whole body motions of a humanoid robot. The methodology consists of three processes: (a) Human modeling, (b) Kinematic mapping and (c) Dynamic mapping. The human modeling based on optimization gives the ZMP (Zero Moment Point) and COM (Center of Mass) time trajectories of an actor. Those trajectories are modified for a humanoid robot through the kinematic mapping. In addition to modifying the ZMP and COM trajectories, the lower body (pelvis and legs) motion of the actor is then scaled kinematically and converted to the motion available to the humanoid robot considering dynamical aspects. The KIST humanoid robot, Mahru, imitated a dancing motion to evaluate the methodology, showing the good agreement in the motion.

• 한국항공우주학회지
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• 제42권3호
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• pp.213-220
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• 2014

본 연구에서는 헬리콥터의 간섭유동장을 고려한 발사체의 궤적예측 프로그램을 개발하였다. 헬리콥터의 간섭유동장 해석에는 엑츄에이터 디스크 모델이 적용된 압축성 비점성 해석자를 이용하였다. 발사체의 궤적 해석에는 6자유도 운동방정식과 대안적 형태의 수정된 질점 운동방정식을 사용하였다. 헬리콥터 주위 유동 해석은 ROBIN(ROtor Body INteraction) 모델을 이용하여 검증하였다. Sierra International 탄과 105mm 포탄의 궤적을 이용해 운동 해석 모듈을 검증하였다. 헬리콥터에서 발사된 발사체의 궤적 예측에는 Sierra International 탄과 HYDRA 70 로켓을 이용하였다.