• 대한토목학회논문집
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• 제31권4A호
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• pp.311-321
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• 2011

RC 슬래브에 배근되는 철근비와 충격체의 충돌속도가 국부손상에 미치는 영향을 평가하기 위하여 일련의 충돌해석을 수행하였다. 해석결과, 철근비는 관입깊이 및 관통두께에 별 다른 영향을 미치지 않았으며, 후면 콘크리트의 탈락면적에는 큰 영향을 미치는 것으로 나타났다. 충격체의 충돌속도가 증가할수록 철근콘크리트 슬래브의 국부손상 정도는 증가하는 경향을 보였다. 이상의 해석결과는 격납건물 및 구조물의 내충격설계시 유용한 자료로 활용될 수 있을 것으로 기대된다.

• 대한기계학회논문집
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• 제18권12호
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• pp.3185-3194
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• 1994

In this study, an impact model and impact response analysis method was suggested for the impacts between arbitrary shaped bodies. Unlike the impacts between geometrically simple structures, there is no rules to analyze the impacts between general elastic structures First of all, it has been attempted to explain the impoot between arbitrary elastic structures as the elastic deformation of a virtual contact spring in the vicinity of contact points. The contact stiffness and the exponent are determined from the Hertz's contact theory and F. E. analysis. In order to evaluate the validities and limitations of the proposed methods, an impact tester and the miniature of container, missile and isolators have been provided and tested experimentally. All the experiments were performed with various impact conditions. The results obtained by the proposed methods were directly compared with the measured values in terms of maximum contract force, contact duration, the shape of contact force and the structure responses. The computed contact force and responses, using this proposed methods, were very close to the measured results, unless any plastic deformations were presented.

• 한국항공우주학회지
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• 제35권7호
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• pp.633-639
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• 2007

본 논문에서는 비행시간과 충돌각을 동시에 제어하기 위한 새로운 호밍 유도법칙을 제안한다. 제안한 유도법칙은 기존의 충돌각 제어 유도법칙인 BPN을 근간으로 비행시간 제어를 위한 제어명령을 부가한다. 부가되는 제어명령은 요구되는 비행시간과 추정된 잔여 비행시간과의 오차로 구성되는 시변이득을 이용하여 산출한다. 따라서 비행시간 오차가 없는 경우 제안한 유도법칙은 BPN으로 수렴되어 안정된 호밍 루프를 구성하게 된다. 시뮬레이션을 통해 제안한 유도법칙의 성능을 확인한다.

• 해양안보
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• 제1권1호
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• pp.241-271
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• 2020

극초음속 미사일은 전 세계에서 가장 많은 관심을 받는 군사기술이다. 러시아, 중국, 미국이 주도하고 있고 다른 나라 역시 경쟁적으로 동참하고 있다. 극초음속 미사일은 탄도미사일과 순항미사일의 장점을 모두 혼합한 미사일로 기존 방어체계로는 요격이 쉽지 않다. 해군은 기술군으로 과학기술 발전은 해양전략에 많은 영향을 미쳐왔다. 해양전략의 핵심은 해양통제다. 이는 점령보다 해양의 사용권리에 대한 문제이며 확보는 수단이고 행사하는 것이 그 목적이다. 극초음속 미사일은 해양통제의 확보 면에서 제한요인으로 작용한다. 극초음속 미사일의 빠른 속력과 강력한 파괴력은 요격이 어려울 뿐만 아니라 단 한발에도 손상통제가 의미없는 수준의 피해가 발생한다. 이로 인해 해양거부능력이 지리적, 질적으로 향상됨에 따라 해양통제 달성이 어려워 질 것이다. 극초음속 미사일은 해양력투사/방어, 해상교통로 공격/방어라는 해양통제 행사면에서는 각각 기회요인과 제한요인으로 동시에 작용한다.

• 한국전자파학회논문지
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• 제21권9호
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• pp.947-954
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• 2010

지상 기동 장비용 펄스 도플러 레이더에서 표적에 대한 위협 판단이 매우 중요하다. 위협 판단은 방위각 변화율에 따라 결정되고, 정확한 방위각 계산에 의해 위협 판단 성능이 좋아지기 때문에 방위각 계산 알고리즘이 매우 중요하다. 방위각 변화율은 접근하는 표적의 방향에 관계되며, 표적은 방위각 변화율의 경계 값에 따라 위협 또는 비위협으로 구분된다. 본 논문은 8개의 방위각 계산 방법을 제시하고, 결과를 비교하였다.

• 한국군사과학기술학회지
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• 제25권2호
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• pp.196-209
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• 2022

Driving dynamic characteristics of semi-trailer loaded with precise equipments are very important to protect them from vibration, impact or other disturbances. In this paper, in order to identify the driving dynamic characteristics of the large scale semi-trailer equipped with swivel axle and hydropneumatic suspension unit, Dynamics Modeling & Simulation(M&S) were performed using general Dynamics Analysis Program(RecurDyn V9R2). The semi-trailer was modeled as two types - one is Multi Rigid Body Dynamics(MRBD) model, and the other Rigid-Flexible Body Dynamics(RFlex) one. The natural vibration mode and frequencies of semi-trailer body, acceleration of dummy-weight, pitch, roll and yaw of dummy-weight, swivel axle and hydropneumatic suspension cylinder support structure, and acting force of hydropneumatic suspensions etc. were obtained from the M&S. Additionally frequency analysis were performed using the data of behavior obtained from above M&S. Generally the quantitative results of RFlex are larger than them of MRBD in view of magnitude of the comparable parametric values.

• Steel and Composite Structures
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• 제49권3호
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• pp.325-335
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• 2023

The missile is affected by both spinning and axial motion during its movement, which will have a very adverse impact on the stability and reliability of the missile. This paper regards missiles as cylindrical shell structures with spinning and axial motion. In this article, the forced vibration of carbon nanotube-reinforced composites (CNTRCs) cylindrical shells with spinning motion and axial motion is investigated, in which the clamped-clamped and simply-simply supported boundary conditions are considered. The displacement field is described by the first-order shear theory, and the vibration equation is deduced by using the Euler-Lagrange equation, after dimensionless processing, the dimensionless equation of motion is obtained. The correctness of this paper is verified by comparing with the results of the existing literature, in which the simply-simply supported ends are taken into account. In the end, the effects of different parameters such as spinning velocity, axial velocity, carbon nanotube volume fraction, length thickness ratio and load position on the resonance behavior of cylindrical shells are given. It can be found that these parameters can significantly change the resonance of axially moving and rotating moving CNTRCs cylindrical shells.

• Nuclear Engineering and Technology
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• 제54권4호
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• pp.1394-1405
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• 2022

The importance of ensuring the inherent safety and security has been more emphasized in recent years to demonstrate the integrity of nuclear facilities under external human-induced events (e.g. aircraft crashes). This work suggests a simulation methodology to effectively evaluate the impact of a commercial aircraft engine onto a dry storage facility. A full-scale engine model was developed and verified by Riera force-time history analysis. A reinforced concrete (RC) structure of a dry storage facility was also developed and material behavior of concrete was incorporated using three constitutive models namely: Continuous Surface Cap, Winfrith, and Karagozian & Case for comparison. Strain-based erosion limits for concrete were suitably defined and the local responses were then compared and analyzed with empirical formulas according to variations in impact velocity. The proposed methodology reasonably predicted such local damage modes of RC structure from the engine missile, and the analysis results agreed well with the calculations of empirical formulas. This research is expected to be helpful in reviewing the dry storage facility design and in the probabilistic risk assessment considering diverse impact scenarios.

• Wind and Structures
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• 제17권2호
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• pp.185-202
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• 2013

The goal of this study was to investigate the vulnerability of roof tile systems and metal shutters to roof tile debris. Three phases addressed the performance of tile roof systems and metal shutters impacted by roof tile debris. The first phase experimentally evaluated the tile fragment size and quantity generated by a tile striking a tile roof system. The second phase experimentally quantified the puncture vulnerability of common metal panel shutter systems as a function of tile fragment impact speed. The third phase provided context for interpretation of the experimental results through the use of a tile trajectory model. The results provide supporting evidence that while metal panel window shutters provide significant protection against a prevalent form of windborne debris, these systems are vulnerable to tile fragment puncture in design level tropical cyclones. These findings correlate with field observations made after Hurricane Charley (2004).

• International Journal of Aeronautical and Space Sciences
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• 제15권2호
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• pp.146-152
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• 2014

In this paper, a new adaptive nonsingular terminal sliding mode control theory based impact angle guidance law for intercepting maneuvering targets was documented. In the design procedure, a new adaptive law for target acceleration bound estimation was presented, which allowed the proposed guidance law to be used without the requirement of the information on the target maneuvering profiles. With the aid of Lyapunov stability criteria, the finite-time convergent characteristics of the line-of-sight angle and its derivative were proven in theory. Numerical simulations were also performed under various conditions to demonstrate the effectiveness of the proposed guidance law.